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This section describes command-line options that are primarily of interest to GCC developers, including options to support compiler testing and investigation of compiler bugs and compile-time performance problems. This includes options that produce debug dumps at various points in the compilation; that print statistics such as memory use and execution time; and that print information about GCC’s configuration, such as where it searches for libraries. You should rarely need to use any of these options for ordinary compilation and linking tasks.
Many developer options that cause GCC to dump output to a file take an
optional ‘=filename’ suffix. You can specify ‘stdout’
or ‘-’ to dump to standard output, and ‘stderr’ for standard
error.
If ‘=filename’ is omitted, a default dump file name is
constructed by concatenating the base dump file name, a pass number,
phase letter, and pass name. The base dump file name is the name of
output file produced by the compiler if explicitly specified and not
an executable; otherwise it is the source file name.
The pass number is determined by the order passes are registered with
the compiler’s pass manager.
This is generally the same as the order of execution, but passes
registered by plugins, target-specific passes, or passes that are
otherwise registered late are numbered higher than the pass named
‘final’, even if they are executed earlier. The phase letter is
one of ‘i’ (inter-procedural analysis), ‘l’
(language-specific), ‘r’ (RTL), or ‘t’ (tree).
The files are created in the directory of the output file.
-fcallgraph-info-fcallgraph-info=MARKERS
Makes the compiler output callgraph information for the program, on a
per-object-file basis. The information is generated in the common VCG
format. It can be decorated with additional, per-node and/or per-edge
information, if a list of comma-separated markers is additionally
specified. When the su marker is specified, the callgraph is
decorated with stack usage information; it is equivalent to
-fstack-usage. When the da marker is specified, the
callgraph is decorated with information about dynamically allocated
objects.
When compiling with -flto, no callgraph information is output
along with the object file. At LTO link time, -fcallgraph-info
may generate multiple callgraph information files next to intermediate
LTO output files.
-dletters-fdump-rtl-pass-fdump-rtl-pass=filename
Says to make debugging dumps during compilation at times specified by
letters. This is used for debugging the RTL-based passes of the
compiler.
Some -dletters switches have different meaning when
-E is used for preprocessing. See Preprocessor Options,
for information about preprocessor-specific dump options.
Debug dumps can be enabled with a -fdump-rtl switch or some
-d option letters. Here are the possible
letters for use in pass and letters, and their meanings:
-fdump-rtl-alignments
Dump after branch alignments have been computed.
-fdump-rtl-asmcons
Dump after fixing rtl statements that have unsatisfied in/out constraints.
-fdump-rtl-auto_inc_dec
Dump after auto-inc-dec discovery. This pass is only run on architectures that have auto inc or auto dec instructions.
-fdump-rtl-barriers
Dump after cleaning up the barrier instructions.
-fdump-rtl-bbpart
Dump after partitioning hot and cold basic blocks.
-fdump-rtl-bbro
Dump after block reordering.
-fdump-rtl-btl1-fdump-rtl-btl2
-fdump-rtl-btl1 and -fdump-rtl-btl2 enable dumping
after the two branch
target load optimization passes.
-fdump-rtl-bypass
Dump after jump bypassing and control flow optimizations.
-fdump-rtl-combine
Dump after the RTL instruction combination pass.
-fdump-rtl-compgotos
Dump after duplicating the computed gotos.
-fdump-rtl-ce1-fdump-rtl-ce2-fdump-rtl-ce3
-fdump-rtl-ce1, -fdump-rtl-ce2, and
-fdump-rtl-ce3 enable dumping after the three
if conversion passes.
-fdump-rtl-cprop_hardreg
Dump after hard register copy propagation.
-fdump-rtl-csa
Dump after combining stack adjustments.
-fdump-rtl-cse1-fdump-rtl-cse2
-fdump-rtl-cse1 and -fdump-rtl-cse2 enable dumping after
the two common subexpression elimination passes.
-fdump-rtl-dce
Dump after the standalone dead code elimination passes.
-fdump-rtl-dbr
Dump after delayed branch scheduling.
-fdump-rtl-dce1-fdump-rtl-dce2
-fdump-rtl-dce1 and -fdump-rtl-dce2 enable dumping after
the two dead store elimination passes.
-fdump-rtl-eh
Dump after finalization of EH handling code.
-fdump-rtl-eh_ranges
Dump after conversion of EH handling range regions.
-fdump-rtl-expand
Dump after RTL generation.
-fdump-rtl-fwprop1-fdump-rtl-fwprop2
-fdump-rtl-fwprop1 and -fdump-rtl-fwprop2 enable
dumping after the two forward propagation passes.
-fdump-rtl-gcse1-fdump-rtl-gcse2
-fdump-rtl-gcse1 and -fdump-rtl-gcse2 enable dumping
after global common subexpression elimination.
-fdump-rtl-init-regs
Dump after the initialization of the registers.
-fdump-rtl-initvals
Dump after the computation of the initial value sets.
-fdump-rtl-into_cfglayout
Dump after converting to cfglayout mode.
-fdump-rtl-ira
Dump after iterated register allocation.
-fdump-rtl-jump
Dump after the second jump optimization.
-fdump-rtl-loop2
-fdump-rtl-loop2 enables dumping after the rtl
loop optimization passes.
-fdump-rtl-mach
Dump after performing the machine dependent reorganization pass, if that pass exists.
-fdump-rtl-mode_sw
Dump after removing redundant mode switches.
-fdump-rtl-rnreg
Dump after register renumbering.
-fdump-rtl-outof_cfglayout
Dump after converting from cfglayout mode.
-fdump-rtl-peephole2
Dump after the peephole pass.
-fdump-rtl-postreload
Dump after post-reload optimizations.
-fdump-rtl-pro_and_epilogue
Dump after generating the function prologues and epilogues.
-fdump-rtl-sched1-fdump-rtl-sched2
-fdump-rtl-sched1 and -fdump-rtl-sched2 enable dumping
after the basic block scheduling passes.
-fdump-rtl-ree
Dump after sign/zero extension elimination.
-fdump-rtl-seqabstr
Dump after common sequence discovery.
-fdump-rtl-shorten
Dump after shortening branches.
-fdump-rtl-sibling
Dump after sibling call optimizations.
-fdump-rtl-split1-fdump-rtl-split2-fdump-rtl-split3-fdump-rtl-split4-fdump-rtl-split5
These options enable dumping after five rounds of instruction splitting.
-fdump-rtl-sms
Dump after modulo scheduling. This pass is only run on some architectures.
-fdump-rtl-stack
Dump after conversion from GCC’s “flat register file” registers to the x87’s stack-like registers. This pass is only run on x86 variants.
-fdump-rtl-subreg1-fdump-rtl-subreg2
-fdump-rtl-subreg1 and -fdump-rtl-subreg2 enable dumping after
the two subreg expansion passes.
-fdump-rtl-unshare
Dump after all rtl has been unshared.
-fdump-rtl-vartrack
Dump after variable tracking.
-fdump-rtl-vregs
Dump after converting virtual registers to hard registers.
-fdump-rtl-web
Dump after live range splitting.
-fdump-rtl-regclass-fdump-rtl-subregs_of_mode_init-fdump-rtl-subregs_of_mode_finish-fdump-rtl-dfinit-fdump-rtl-dfinish
These dumps are defined but always produce empty files.
-da-fdump-rtl-all
Produce all the dumps listed above.
-dA
Annotate the assembler output with miscellaneous debugging information.
-dD
Dump all macro definitions, at the end of preprocessing, in addition to normal output.
-dH
Produce a core dump whenever an error occurs.
-dp
Annotate the assembler output with a comment indicating which pattern and alternative is used. The length and cost of each instruction are also printed.
-dP
Dump the RTL in the assembler output as a comment before each instruction.
Also turns on -dp annotation.
-dx
Just generate RTL for a function instead of compiling it. Usually used
with -fdump-rtl-expand.
-fdump-debug
Dump debugging information generated during the debug generation phase.
-fdump-earlydebug
Dump debugging information generated during the early debug generation phase.
-fdump-noaddr
When doing debugging dumps, suppress address output. This makes it more feasible to use diff on debugging dumps for compiler invocations with different compiler binaries and/or different text / bss / data / heap / stack / dso start locations.
-freport-bug
Collect and dump debug information into a temporary file if an internal compiler error (ICE) occurs.
-fdump-unnumbered
When doing debugging dumps, suppress instruction numbers and address output.
This makes it more feasible to use diff on debugging dumps for compiler
invocations with different options, in particular with and without
-g.
-fdump-unnumbered-links
When doing debugging dumps (see -d option above), suppress
instruction numbers for the links to the previous and next instructions
in a sequence.
-fdump-ipa-switch-fdump-ipa-switch-options
Control the dumping at various stages of inter-procedural analysis language tree to a file. The file name is generated by appending a switch specific suffix to the source file name, and the file is created in the same directory as the output file. The following dumps are possible:
all’Enables all inter-procedural analysis dumps.
cgraph’Dumps information about call-graph optimization, unused function removal, and inlining decisions.
inline’Dump after function inlining.
Additionally, the options -optimized, -missed,
-note, and -all can be provided, with the same meaning
as for -fopt-info, defaulting to -optimized.
For example, -fdump-ipa-inline-optimized-missed will emit
information on callsites that were inlined, along with callsites
that were not inlined.
By default, the dump will contain messages about successful
optimizations (equivalent to -optimized) together with
low-level details about the analysis.
-fdump-lang-all-fdump-lang-switch-fdump-lang-switch-options-fdump-lang-switch-options=filename
Control the dumping of language-specific information. The options
and filename portions behave as described in the
-fdump-tree option. The following switch values are
accepted:
all’Enable all language-specific dumps.
class’Dump class hierarchy information. Virtual table information is emitted
unless ’slim’ is specified. This option is applicable to C++ only.
raw’Dump the raw internal tree data. This option is applicable to C++ only.
-fdump-passes
Print on stderr the list of optimization passes that are turned
on and off by the current command-line options.
-fdump-statistics-option
Enable and control dumping of pass statistics in a separate file. The
file name is generated by appending a suffix ending in
‘.statistics’ to the source file name, and the file is created in
the same directory as the output file. If the ‘-option’
form is used, ‘-stats’ causes counters to be summed over the
whole compilation unit while ‘-details’ dumps every event as
the passes generate them. The default with no option is to sum
counters for each function compiled.
-fdump-tree-all-fdump-tree-switch-fdump-tree-switch-options-fdump-tree-switch-options=filename
Control the dumping at various stages of processing the intermediate
language tree to a file. If the ‘-options’
form is used, options is a list of ‘-’ separated options
which control the details of the dump. Not all options are applicable
to all dumps; those that are not meaningful are ignored. The
following options are available
address’Print the address of each node. Usually this is not meaningful as it changes according to the environment and source file. Its primary use is for tying up a dump file with a debug environment.
asmname’If DECL_ASSEMBLER_NAME has been set for a given decl, use that
in the dump instead of DECL_NAME. Its primary use is ease of
use working backward from mangled names in the assembly file.
slim’When dumping front-end intermediate representations, inhibit dumping of members of a scope or body of a function merely because that scope has been reached. Only dump such items when they are directly reachable by some other path.
When dumping pretty-printed trees, this option inhibits dumping the bodies of control structures.
When dumping RTL, print the RTL in slim (condensed) form instead of the default LISP-like representation.
raw’Print a raw representation of the tree. By default, trees are pretty-printed into a C-like representation.
details’Enable more detailed dumps (not honored by every dump option). Also include information from the optimization passes.
stats’Enable dumping various statistics about the pass (not honored by every dump option).
blocks’Enable showing basic block boundaries (disabled in raw dumps).
graph’For each of the other indicated dump files (-fdump-rtl-pass),
dump a representation of the control flow graph suitable for viewing with
GraphViz to file.passid.pass.dot. Each function in
the file is pretty-printed as a subgraph, so that GraphViz can render them
all in a single plot.
This option currently only works for RTL dumps, and the RTL is always dumped in slim form.
vops’Enable showing virtual operands for every statement.
lineno’Enable showing line numbers for statements.
uid’Enable showing the unique ID (DECL_UID) for each variable.
verbose’Enable showing the tree dump for each statement.
eh’Enable showing the EH region number holding each statement.
scev’Enable showing scalar evolution analysis details.
optimized’Enable showing optimization information (only available in certain passes).
missed’Enable showing missed optimization information (only available in certain passes).
note’Enable other detailed optimization information (only available in certain passes).
all’Turn on all options, except raw, slim, verbose
and lineno.
optall’Turn on all optimization options, i.e., optimized,
missed, and note.
To determine what tree dumps are available or find the dump for a pass of interest follow the steps below.
-fdump-passes and in the stderr output
look for a code that corresponds to the pass you are interested in.
For example, the codes tree-evrp, tree-vrp1, and
tree-vrp2 correspond to the three Value Range Propagation passes.
The number at the end distinguishes distinct invocations of the same pass.-fdump- option prefix and invoke GCC with it. For example,
to enable the dump from the Early Value Range Propagation pass, invoke
GCC with the -fdump-tree-evrp option. Optionally, you may
specify the name of the dump file. If you don’t specify one, GCC
creates as described below.t’ for tree passes (and the letter ‘r’ for RTL passes),
and finally the pass code. For example, the Early VRP pass dump might
be in a file named myfile.c.038t.evrp in the current working
directory. Note that the numeric codes are not stable and may change
from one version of GCC to another.-fopt-info-fopt-info-options-fopt-info-options=filename
Controls optimization dumps from various optimization passes. If the
‘-options’ form is used, options is a list of
‘-’ separated option keywords to select the dump details and
optimizations.
The options can be divided into three groups:
The options from each group can be freely mixed as they are non-overlapping. However, in case of any conflicts, the later options override the earlier options on the command line.
The following options control which kinds of messages should be emitted:
optimized’Print information when an optimization is successfully applied. It is up to a pass to decide which information is relevant. For example, the vectorizer passes print the source location of loops which are successfully vectorized.
missed’Print information about missed optimizations. Individual passes control which information to include in the output.
note’Print verbose information about optimizations, such as certain transformations, more detailed messages about decisions etc.
all’Print detailed optimization information. This includes
‘optimized’, ‘missed’, and ‘note’.
The following option controls the dump verbosity:
internals’By default, only “high-level” messages are emitted. This option enables additional, more detailed, messages, which are likely to only be of interest to GCC developers.
One or more of the following option keywords can be used to describe a group of optimizations:
ipa’Enable dumps from all interprocedural optimizations.
loop’Enable dumps from all loop optimizations.
inline’Enable dumps from all inlining optimizations.
omp’Enable dumps from all OMP (Offloading and Multi Processing) optimizations.
vec’Enable dumps from all vectorization optimizations.
optall’Enable dumps from all optimizations. This is a superset of the optimization groups listed above.
If options is
omitted, it defaults to ‘optimized-optall’, which means to dump messages
about successful optimizations from all the passes, omitting messages
that are treated as “internals”.
If the filename is provided, then the dumps from all the
applicable optimizations are concatenated into the filename.
Otherwise the dump is output onto stderr. Though multiple
-fopt-info options are accepted, only one of them can include
a filename. If other filenames are provided then all but the
first such option are ignored.
Note that the output filename is overwritten
in case of multiple translation units. If a combined output from
multiple translation units is desired, stderr should be used
instead.
In the following example, the optimization info is output to
stderr:
gcc -O3 -fopt-info
This example:
gcc -O3 -fopt-info-missed=missed.all
outputs missed optimization report from all the passes into
missed.all, and this one:
gcc -O2 -ftree-vectorize -fopt-info-vec-missed
prints information about missed optimization opportunities from
vectorization passes on stderr.
Note that -fopt-info-vec-missed is equivalent to
-fopt-info-missed-vec. The order of the optimization group
names and message types listed after -fopt-info does not matter.
As another example,
gcc -O3 -fopt-info-inline-optimized-missed=inline.txt
outputs information about missed optimizations as well as
optimized locations from all the inlining passes into
inline.txt.
Finally, consider:
gcc -fopt-info-vec-missed=vec.miss -fopt-info-loop-optimized=loop.opt
Here the two output filenames vec.miss and loop.opt are
in conflict since only one output file is allowed. In this case, only
the first option takes effect and the subsequent options are
ignored. Thus only vec.miss is produced which contains
dumps from the vectorizer about missed opportunities.
-fsave-optimization-record
Write a SRCFILE.opt-record.json.gz file detailing what optimizations
were performed, for those optimizations that support -fopt-info.
This option is experimental and the format of the data within the compressed JSON file is subject to change.
It is roughly equivalent to a machine-readable version of
-fopt-info-all, as a collection of messages with source file,
line number and column number, with the following additional data for
each message:
Additionally, some messages are logically nested within other messages, reflecting implementation details of the optimization passes.
-fsched-verbose=n
On targets that use instruction scheduling, this option controls the amount of debugging output the scheduler prints to the dump files.
For n greater than zero, -fsched-verbose outputs the
same information as -fdump-rtl-sched1 and -fdump-rtl-sched2.
For n greater than one, it also output basic block probabilities,
detailed ready list information and unit/insn info. For n greater
than two, it includes RTL at abort point, control-flow and regions info.
And for n over four, -fsched-verbose also includes
dependence info.
-fenable-kind-pass-fdisable-kind-pass=range-list
This is a set of options that are used to explicitly disable/enable optimization passes. These options are intended for use for debugging GCC. Compiler users should use regular options for enabling/disabling passes instead.
-fdisable-ipa-passDisable IPA pass pass. pass is the pass name. If the same pass is
statically invoked in the compiler multiple times, the pass name should be
appended with a sequential number starting from 1.
-fdisable-rtl-pass-fdisable-rtl-pass=range-listDisable RTL pass pass. pass is the pass name. If the same pass is
statically invoked in the compiler multiple times, the pass name should be
appended with a sequential number starting from 1. range-list is a
comma-separated list of function ranges or assembler names. Each range is a number
pair separated by a colon. The range is inclusive in both ends. If the range
is trivial, the number pair can be simplified as a single number. If the
function’s call graph node’s uid falls within one of the specified ranges,
the pass is disabled for that function. The uid is shown in the
function header of a dump file, and the pass names can be dumped by using
option -fdump-passes.
-fdisable-tree-pass-fdisable-tree-pass=range-listDisable tree pass pass. See -fdisable-rtl for the description of
option arguments.
-fenable-ipa-passEnable IPA pass pass. pass is the pass name. If the same pass is
statically invoked in the compiler multiple times, the pass name should be
appended with a sequential number starting from 1.
-fenable-rtl-pass-fenable-rtl-pass=range-listEnable RTL pass pass. See -fdisable-rtl for option argument
description and examples.
-fenable-tree-pass-fenable-tree-pass=range-listEnable tree pass pass. See -fdisable-rtl for the description
of option arguments.
Here are some examples showing uses of these options.
# disable ccp1 for all functions -fdisable-tree-ccp1 # disable complete unroll for function whose cgraph node uid is 1 -fenable-tree-cunroll=1 # disable gcse2 for functions at the following ranges [1,1], # [300,400], and [400,1000] # disable gcse2 for functions foo and foo2 -fdisable-rtl-gcse2=foo,foo2 # disable early inlining -fdisable-tree-einline # disable ipa inlining -fdisable-ipa-inline # enable tree full unroll -fenable-tree-unroll
-fchecking-fchecking=n
Enable internal consistency checking. The default depends on
the compiler configuration. -fchecking=2 enables further
internal consistency checking that might affect code generation.
-frandom-seed=string
This option provides a seed that GCC uses in place of
random numbers in generating certain symbol names
that have to be different in every compiled file. It is also used to
place unique stamps in coverage data files and the object files that
produce them. You can use the -frandom-seed option to produce
reproducibly identical object files.
The string can either be a number (decimal, octal or hex) or an
arbitrary string (in which case it’s converted to a number by
computing CRC32).
The string should be different for every file you compile.
-save-temps-save-temps=cwd
Store the usual “temporary” intermediate files permanently; place them
in the current directory and name them based on the source file. Thus,
compiling foo.c with -c -save-temps produces files
foo.i and foo.s, as well as foo.o. This creates a
preprocessed foo.i output file even though the compiler now
normally uses an integrated preprocessor.
When used in combination with the -x command-line option,
-save-temps is sensible enough to avoid over writing an
input source file with the same extension as an intermediate file.
The corresponding intermediate file may be obtained by renaming the
source file before using -save-temps.
If you invoke GCC in parallel, compiling several different source files that share a common base name in different subdirectories or the same source file compiled for multiple output destinations, it is likely that the different parallel compilers will interfere with each other, and overwrite the temporary files. For instance:
gcc -save-temps -o outdir1/foo.o indir1/foo.c& gcc -save-temps -o outdir2/foo.o indir2/foo.c&
may result in foo.i and foo.o being written to
simultaneously by both compilers.
-save-temps=obj
Store the usual “temporary” intermediate files permanently. If the
-o option is used, the temporary files are based on the
object file. If the -o option is not used, the
-save-temps=obj switch behaves like -save-temps.
For example:
gcc -save-temps=obj -c foo.c gcc -save-temps=obj -c bar.c -o dir/xbar.o gcc -save-temps=obj foobar.c -o dir2/yfoobar
creates foo.i, foo.s, dir/xbar.i,
dir/xbar.s, dir2/yfoobar.i, dir2/yfoobar.s, and
dir2/yfoobar.o.
-time[=file]
Report the CPU time taken by each subprocess in the compilation sequence. For C source files, this is the compiler proper and assembler (plus the linker if linking is done).
Without the specification of an output file, the output looks like this:
# cc1 0.12 0.01 # as 0.00 0.01
The first number on each line is the “user time”, that is time spent executing the program itself. The second number is “system time”, time spent executing operating system routines on behalf of the program. Both numbers are in seconds.
With the specification of an output file, the output is appended to the named file, and it looks like this:
0.12 0.01 cc1 options 0.00 0.01 as options
The “user time” and the “system time” are moved before the program name, and the options passed to the program are displayed, so that one can later tell what file was being compiled, and with which options.
-fdump-final-insns[=file]
Dump the final internal representation (RTL) to file. If the
optional argument is omitted (or if file is .), the name
of the dump file is determined by appending .gkd to the
compilation output file name.
-fcompare-debug[=opts]
If no error occurs during compilation, run the compiler a second time,
adding opts and -fcompare-debug-second to the arguments
passed to the second compilation. Dump the final internal
representation in both compilations, and print an error if they differ.
If the equal sign is omitted, the default -gtoggle is used.
The environment variable GCC_COMPARE_DEBUG, if defined, non-empty
and nonzero, implicitly enables -fcompare-debug. If
GCC_COMPARE_DEBUG is defined to a string starting with a dash,
then it is used for opts, otherwise the default -gtoggle
is used.
-fcompare-debug=, with the equal sign but without opts,
is equivalent to -fno-compare-debug, which disables the dumping
of the final representation and the second compilation, preventing even
GCC_COMPARE_DEBUG from taking effect.
To verify full coverage during -fcompare-debug testing, set
GCC_COMPARE_DEBUG to say -fcompare-debug-not-overridden,
which GCC rejects as an invalid option in any actual compilation
(rather than preprocessing, assembly or linking). To get just a
warning, setting GCC_COMPARE_DEBUG to ‘-w%n-fcompare-debug not overridden’ will do.
-fcompare-debug-second
This option is implicitly passed to the compiler for the second
compilation requested by -fcompare-debug, along with options to
silence warnings, and omitting other options that would cause the compiler
to produce output to files or to standard output as a side effect. Dump
files and preserved temporary files are renamed so as to contain the
.gk additional extension during the second compilation, to avoid
overwriting those generated by the first.
When this option is passed to the compiler driver, it causes the first compilation to be skipped, which makes it useful for little other than debugging the compiler proper.
-gtoggle
Turn off generation of debug info, if leaving out this option
generates it, or turn it on at level 2 otherwise. The position of this
argument in the command line does not matter; it takes effect after all
other options are processed, and it does so only once, no matter how
many times it is given. This is mainly intended to be used with
-fcompare-debug.
-fvar-tracking-assignments-toggle
Toggle -fvar-tracking-assignments, in the same way that
-gtoggle toggles -g.
-Q
Makes the compiler print out each function name as it is compiled, and print some statistics about each pass when it finishes.
-ftime-report
Makes the compiler print some statistics about the time consumed by each pass when it finishes.
-ftime-report-details
Record the time consumed by infrastructure parts separately for each pass.
-fira-verbose=n
Control the verbosity of the dump file for the integrated register allocator.
The default value is 5. If the value n is greater or equal to 10,
the dump output is sent to stderr using the same format as n minus 10.
-flto-report
Prints a report with internal details on the workings of the link-time
optimizer. The contents of this report vary from version to version.
It is meant to be useful to GCC developers when processing object
files in LTO mode (via -flto).
Disabled by default.
-flto-report-wpa
Like -flto-report, but only print for the WPA phase of link-time
optimization.
-fmem-report
Makes the compiler print some statistics about permanent memory allocation when it finishes.
-fmem-report-wpa
Makes the compiler print some statistics about permanent memory allocation for the WPA phase only.
-fpre-ipa-mem-report-fpost-ipa-mem-report
Makes the compiler print some statistics about permanent memory allocation before or after interprocedural optimization.
-fprofile-report
Makes the compiler print some statistics about consistency of the (estimated) profile and effect of individual passes.
-fstack-usage
Makes the compiler output stack usage information for the program, on a
per-function basis. The filename for the dump is made by appending
.su to the auxname. auxname is generated from the name of
the output file, if explicitly specified and it is not an executable,
otherwise it is the basename of the source file. An entry is made up
of three fields:
static, dynamic, bounded.The qualifier static means that the function manipulates the stack
statically: a fixed number of bytes are allocated for the frame on function
entry and released on function exit; no stack adjustments are otherwise made
in the function. The second field is this fixed number of bytes.
The qualifier dynamic means that the function manipulates the stack
dynamically: in addition to the static allocation described above, stack
adjustments are made in the body of the function, for example to push/pop
arguments around function calls. If the qualifier bounded is also
present, the amount of these adjustments is bounded at compile time and
the second field is an upper bound of the total amount of stack used by
the function. If it is not present, the amount of these adjustments is
not bounded at compile time and the second field only represents the
bounded part.
-fstats
Emit statistics about front-end processing at the end of the compilation. This option is supported only by the C++ front end, and the information is generally only useful to the G++ development team.
-fdbg-cnt-list
Print the name and the counter upper bound for all debug counters.
-fdbg-cnt=counter-value-list
Set the internal debug counter lower and upper bound. counter-value-list
is a comma-separated list of name:lower_bound1-upper_bound1
[:lower_bound2-upper_bound2...] tuples which sets
the name of the counter and list of closed intervals.
The lower_bound is optional and is zero
initialized if not set.
For example, with -fdbg-cnt=dce:2-4:10-11,tail_call:10,
dbg_cnt(dce) returns true only for second, third, fourth, tenth and
eleventh invocation.
For dbg_cnt(tail_call) true is returned for first 10 invocations.
-print-file-name=library
Print the full absolute name of the library file library that
would be used when linking—and don’t do anything else. With this
option, GCC does not compile or link anything; it just prints the
file name.
-print-multi-directory
Print the directory name corresponding to the multilib selected by any
other switches present in the command line. This directory is supposed
to exist in GCC_EXEC_PREFIX.
-print-multi-lib
Print the mapping from multilib directory names to compiler switches
that enable them. The directory name is separated from the switches by
‘;’, and each switch starts with an ‘@’ instead of the
‘-’, without spaces between multiple switches. This is supposed to
ease shell processing.
-print-multi-os-directory
Print the path to OS libraries for the selected
multilib, relative to some lib subdirectory. If OS libraries are
present in the lib subdirectory and no multilibs are used, this is
usually just ., if OS libraries are present in libsuffix
sibling directories this prints e.g. ../lib64, ../lib or
../lib32, or if OS libraries are present in lib/subdir
subdirectories it prints e.g. amd64, sparcv9 or ev6.
-print-multiarch
Print the path to OS libraries for the selected multiarch,
relative to some lib subdirectory.
-print-prog-name=program
Like -print-file-name, but searches for a program such as cpp.
-print-libgcc-file-name
Same as -print-file-name=libgcc.a.
This is useful when you use -nostdlib or -nodefaultlibs
but you do want to link with libgcc.a. You can do:
gcc -nostdlib files… `gcc -print-libgcc-file-name`
-print-search-dirs
Print the name of the configured installation directory and a list of
program and library directories gcc searches—and don’t do anything else.
This is useful when gcc prints the error message
‘installation problem, cannot exec cpp0: No such file or directory’.
To resolve this you either need to put cpp0 and the other compiler
components where gcc expects to find them, or you can set the environment
variable GCC_EXEC_PREFIX to the directory where you installed them.
Don’t forget the trailing ‘/’.
See Environment Variables.
-print-sysroot
Print the target sysroot directory that is used during
compilation. This is the target sysroot specified either at configure
time or using the --sysroot option, possibly with an extra
suffix that depends on compilation options. If no target sysroot is
specified, the option prints nothing.
-print-sysroot-headers-suffix
Print the suffix added to the target sysroot when searching for headers, or give an error if the compiler is not configured with such a suffix—and don’t do anything else.
-dumpmachine
Print the compiler’s target machine (for example,
‘i686-pc-linux-gnu’)—and don’t do anything else.
-dumpversion
Print the compiler version (for example, 3.0, 6.3.0 or 7)—and don’t do
anything else. This is the compiler version used in filesystem paths and
specs. Depending on how the compiler has been configured it can be just
a single number (major version), two numbers separated by a dot (major and
minor version) or three numbers separated by dots (major, minor and patchlevel
version).
-dumpfullversion
Print the full compiler version—and don’t do anything else. The output is always three numbers separated by dots, major, minor and patchlevel version.
-dumpspecs
Print the compiler’s built-in specs—and don’t do anything else. (This is used when GCC itself is being built.) See Spec Files.
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