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[NFC][InstCombine] Add a test for assume-induced miscompile 

@escape() may throw here, we don't know that assumption, which is located
afterwards in the same block, is executed, therefore %load arg of
call to @escape() can not be marked as non-null.

As noted in D71660 review by @nikic.
This commit is contained in:
Roman Lebedev 2019-12-20 00:04:31 +03:00
parent caaacb8399
commit ffcae008d7
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llvm/test/Transforms/InstCombine/assume.ll
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@ -311,6 +311,23 @@ define i1 @nonnull4(i32** %a) {
%rval = icmp eq i32* %load, null %rval = icmp eq i32* %load, null
ret i1 %rval ret i1 %rval
} }
define i1 @nonnull5(i32** %a) {
; CHECK-LABEL: @nonnull5(
; CHECK-NEXT: [[LOAD:%.*]] = load i32*, i32** [[A:%.*]], align 8
; CHECK-NEXT: tail call void @escape(i32* nonnull [[LOAD]])
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32* [[LOAD]], null
; CHECK-NEXT: tail call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: ret i1 false
;
%load = load i32*, i32** %a
;; This call may throw!
tail call void @escape(i32* %load)
%integral = ptrtoint i32* %load to i64
%cmp = icmp slt i64 %integral, 0
tail call void @llvm.assume(i1 %cmp) ; %load has at least highest bit set
%rval = icmp eq i32* %load, null
ret i1 %rval
}
; PR35846 - https://bugs.llvm.org/show_bug.cgi?id=35846 ; PR35846 - https://bugs.llvm.org/show_bug.cgi?id=35846