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Move createEliminateAvailableExternallyPass earlier in the pass pipeline 

to save running many ModulePasses on available external functions that
are thrown away anyhow.

llvm-svn: 246619
This commit is contained in:
Yaron Keren 2015-09-02 06:34:11 +00:00
parent 2ea5393ca1
commit 611c7cff53
1 changed files with 13 additions and 11 deletions
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24
llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
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@ -331,6 +331,19 @@ void PassManagerBuilder::populateModulePassManager(
// we must insert a no-op module pass to reset the pass manager.
MPM.add(createBarrierNoopPass());
if (!DisableUnitAtATime && OptLevel > 1 && !PrepareForLTO) {
// Remove avail extern fns and globals definitions if we aren't
// compiling an object file for later LTO. For LTO we want to preserve
// these so they are eligible for inlining at link-time. Note if they
// are unreferenced they will be removed by GlobalDCE later, so
// this only impacts referenced available externally globals.
// Eventually they will be suppressed during codegen, but eliminating
// here enables more opportunity for GlobalDCE as it may make
// globals referenced by available external functions dead
// and saves running remaining passes on the eliminated functions.
MPM.add(createEliminateAvailableExternallyPass());
}
if (EnableNonLTOGlobalsModRef)
// We add a fresh GlobalsModRef run at this point. This is particularly
// useful as the above will have inlined, DCE'ed, and function-attr
@ -438,17 +451,6 @@ void PassManagerBuilder::populateModulePassManager(
// GlobalOpt already deletes dead functions and globals, at -O2 try a
// late pass of GlobalDCE. It is capable of deleting dead cycles.
if (OptLevel > 1) {
if (!PrepareForLTO) {
// Remove avail extern fns and globals definitions if we aren't
// compiling an object file for later LTO. For LTO we want to preserve
// these so they are eligible for inlining at link-time. Note if they
// are unreferenced they will be removed by GlobalDCE below, so
// this only impacts referenced available externally globals.
// Eventually they will be suppressed during codegen, but eliminating
// here enables more opportunity for GlobalDCE as it may make
// globals referenced by available external functions dead.
MPM.add(createEliminateAvailableExternallyPass());
}
MPM.add(createGlobalDCEPass()); // Remove dead fns and globals.
MPM.add(createConstantMergePass()); // Merge dup global constants
}