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Unlike bootstrap-debug, bootstrap-debug-lean used to pass compare using the traditional compare command, because it compiled both stage2 and stage3 with options that used to generate identical output (-fcompare-debug= in stage2 vs -fcompare-debug in stage3). Since we started adding relevant command-line flags to DW_AT_producer, this is no longer the case, and stages 2 and 3 object files that differ in nothing but the DW_AT_producer strings. -fcompare-debug is short for -fcompare-debug=-gtoggle, so stage3 compiles twice, once with the normal options, once with toggled -g, to then compare the temporary final dumps. When enabled, both compilations get from the driver an additional -frandom-seed flag (if none is given explicitly). -fcompare-debug= is short for -fno-compare-debug, disabling the second compilation. The difference between the DW_AT_producer lines are the different -fcompare-debug flags, and the presence of the -frandom-seed flag in the stage3 compilation. It is easy and sensible enough to filter the -fcompare-debug flags out of the DW_AT_producer string. This option should never affect the compilation output, it just determines whether or not to perform an additional compilation that should produce the same executable output. However, dropping -frandom-seed is not quite correct, in that it might have other consequences on the compilation. So, it makes little sense to make the effort to drop it when it's implicit; for those comparing compiler output differences, it might even hint at what causes, and could fix, difficult to explain differences, namely, explicitly supplying -frandom-seed options. They don't seem to matter for compiler bootstraps, though, at least for now, so we can safely refrain from issuing -frandom-seed (or maybe we already issue it where needed :-), and then, for bootstrap-debug-lean, use the compare-debug script, that strips out debug information before comparing the object files. for config/ChangeLog * bootstrap-debug-lean.mk (do-compare): Use the contrib/compare-debug script. for gcc/ChangeLog * dwarf2out.c (gen_producer_string): Discard OPT_fcompare_debug. From-SVN: r254750
13 lines
537 B
Makefile
13 lines
537 B
Makefile
# This BUILD_CONFIG option is a bit like bootstrap-debug, but rather
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# than comparing stripped object files, it compares compiler internal
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# state during stage3. Both can be used simultaneously.
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# This makes it slower than bootstrap-debug alone, for there's
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# additional dumping and recompilation during stage3.
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# bootstrap-debug-big can avoid the recompilation, if plenty of disk
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# space is available.
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STAGE2_CFLAGS += -fcompare-debug=
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STAGE3_CFLAGS += -fcompare-debug
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do-compare = $(SHELL) $(srcdir)/contrib/compare-debug $$f1 $$f2
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