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| Differential D65199
[GlobalISel Legalizer][RFC] Legalization artifact combiner AbandonedPublic Authored by Petar.Avramovic on Jul 24 2019, 4:28 AM.
Details
Summary Discussion about Legalization artifact combiner and how to make sure it combines everything it can. Legalization artifact combiner currently leaves uncombined artifacts because they :
Q: What to do with artifact that just failed to combine
Diff Detail Event TimelineComment Actions About 2. we are missing necessary combine About D61787 : When artifact that just failed to combine we check if there is something in some of the lists (InstList, ArtifactList, AuxiliaryArtifactList) that could create other half that is needed for combine. When there is nothing in the lists that could create other half we have to legalize (most likely legal or narrowScalar). Comment Actions Here are two files with -debug outputs from fame input test. One was generated with D61787 other without it. Test file contains: define void @trunc(i32* %i32_ptr_a, i32* %i32_ptr_b) {
entry:
%0 = load i32, i32* %i32_ptr_a, align 4
%tobool = trunc i32 %0 to i1
%frombool2 = sext i1 %tobool to i8
%fromchar3 = zext i8 %frombool2 to i32
store i32 %fromchar3, i32* %i32_ptr_b, align 4
ret void
}
define i64 @merge(i32 %x, i32 %y, i64 %z) {
entry:
%add = add i32 %y, %x
%conv = sext i32 %add to i64
%add1 = add i64 %conv, %z
ret i64 %add1
}In first function zext combine attempt happens first second function has sext narrowscalar Both versions have: differences are: getActionDefinitionsBuilder({G_ZEXT, G_SEXT, G_ANYEXT})
.legalIf([=](const LegalityQuery &Query) {
if (Query.Types[0].getSizeInBits() == 64 &&
Query.Types[1].getSizeInBits() == 32)
return false;
return true;
})
.maxScalar(0, s32);
getActionDefinitionsBuilder(G_TRUNC)
.legalIf([=](const LegalityQuery &Query) { return true; });in "withD61787.txt" artifacts are not legal getActionDefinitionsBuilder({G_ZEXT, G_SEXT, G_ANYEXT})
.legalIf([=](const LegalityQuery &Query) { return false; })
.maxScalar(0, s32);
getActionDefinitionsBuilder(G_TRUNC)
.legalIf([=](const LegalityQuery &Query) { return false; });and D61787 is applied with some additional changes to how -debug prints
Revision Contents
Diff 211466 test/CodeGen/Mips/GlobalISel/llvm-ir/current.txt
test/CodeGen/Mips/GlobalISel/llvm-ir/withD61787.txt
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This one should wait and try combine later, instead it has to be legal in order to continue.