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[CodeGenPrepare] avoid crashing on non-canonical/degenerate code

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The test is reduced from an example in the post-commit thread for:
rL354746
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20190304/632396.html

While we must avoid dying here, the real question should be:
Why is non-canonical and/or degenerate code making it to CGP when
using the new pass manager?

llvm-svn: 355345
This commit is contained in:
Sanjay Patel 2019-03-04 22:47:13 +00:00
parent dd5c010238
commit 8f1017e9ee
2 changed files with 30 additions and 0 deletions
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5
lib/CodeGen/CodeGenPrepare.cpp
View File

@ -1203,6 +1203,11 @@ static bool matchUAddWithOverflowConstantEdgeCases(CmpInst *Cmp,
// Add = add A, 1; Cmp = icmp eq A,-1 (overflow if A is max val)
// Add = add A,-1; Cmp = icmp ne A, 0 (overflow if A is non-zero)
Value *A = Cmp->getOperand(0), *B = Cmp->getOperand(1);
// We are not expecting non-canonical/degenerate code. Just bail out.
if (isa<Constant>(A))
return false;
ICmpInst::Predicate Pred = Cmp->getPredicate();
if (Pred == ICmpInst::ICMP_EQ && match(B, m_AllOnes()))
B = ConstantInt::get(B->getType(), 1);

25
test/Transforms/CodeGenPrepare/X86/overflow-intrinsics.ll
View File

@ -430,6 +430,31 @@ end:
ret i1 %ov
}
; Verify that crazy/non-canonical code does not crash.
define void @bar() {
; CHECK-LABEL: @bar(
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i64 1, -1
; CHECK-NEXT: [[FROMBOOL:%.*]] = zext i1 [[CMP]] to i8
; CHECK-NEXT: unreachable
;
%cmp = icmp eq i64 1, -1
%frombool = zext i1 %cmp to i8
unreachable
}
define void @foo() {
; CHECK-LABEL: @foo(
; CHECK-NEXT: [[SUB:%.*]] = add nsw i64 1, 1
; CHECK-NEXT: [[CONV:%.*]] = trunc i64 [[SUB]] to i32
; CHECK-NEXT: unreachable
;
%sub = add nsw i64 1, 1
%conv = trunc i64 %sub to i32
unreachable
}
; Check that every instruction inserted by -codegenprepare has a debug location.
; DEBUG: CheckModuleDebugify: PASS