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[AggressiveInstCombine] avoid crashing on unsimplified code (PR37446)

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This bug:
https://bugs.llvm.org/show_bug.cgi?id=37446
...raises another question: why do we run aggressive-instcombine before 
regular instcombine?

llvm-svn: 332243
This commit is contained in:
Sanjay Patel 2018-05-14 13:43:32 +00:00
parent 25ecc50bdc
commit 475e9be6be
2 changed files with 20 additions and 0 deletions
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4
lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp
View File

@ -108,6 +108,10 @@ static bool matchAndOrChain(Value *V, MaskOps &MOps) {
if (!MOps.Root)
MOps.Root = Candidate;
// The shift constant is out-of-range? This code hasn't been simplified.
if (BitIndex >= MOps.Mask.getBitWidth())
return false;
// Fill in the mask bit derived from the shift constant.
MOps.Mask.setBit(BitIndex);
return MOps.Root == Candidate;

16
test/Transforms/AggressiveInstCombine/masked-cmp.ll
View File

@ -217,3 +217,19 @@ define i64 @allset_40_bit_mask(i64 %x) {
ret i64 %a40
}
; Verify that unsimplified code doesn't crash:
; https://bugs.llvm.org/show_bug.cgi?id=37446
define i32 @PR37446(i32 %x) {
; CHECK-LABEL: @PR37446(
; CHECK-NEXT: [[SHR:%.*]] = lshr i32 1, 33
; CHECK-NEXT: [[AND:%.*]] = and i32 [[SHR]], 15
; CHECK-NEXT: [[AND1:%.*]] = and i32 [[AND]], [[X:%.*]]
; CHECK-NEXT: ret i32 [[AND1]]
;
%shr = lshr i32 1, 33
%and = and i32 %shr, 15
%and1 = and i32 %and, %x
ret i32 %and1
}