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It is invalid to hoist stores or loads if they are not executed on all paths from the hoisting point to the exit of the function. In the testcase, there are paths in the loop that do not execute the stores or the loads, and so hoisting them within the loop is unsafe. The problem is that the current implementation of hoistingFromAllPaths is incomplete: it walks all blocks dominated by the hoisting point, and does not return false when the loop contains a path on which the hoisted ld/st is not executed. Differential Revision: https://reviews.llvm.org/D23843 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279732 91177308-0d34-0410-b5e6-96231b3b80d8
52 lines
1.5 KiB
LLVM
52 lines
1.5 KiB
LLVM
; RUN: opt -S -gvn-hoist < %s | FileCheck %s
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; Check that the stores are not hoisted: it is invalid to hoist stores if they
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; are not executed on all paths. In this testcase, there are paths in the loop
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; that do not execute the stores.
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; CHECK-LABEL: define i32 @main
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; CHECK: store
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; CHECK: store
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; CHECK: store
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@a = global i32 0, align 4
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define i32 @main() {
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entry:
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br label %for.cond
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for.cond: ; preds = %for.inc5, %entry
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%0 = load i32, i32* @a, align 4
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%cmp = icmp slt i32 %0, 1
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br i1 %cmp, label %for.cond1, label %for.end7
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for.cond1: ; preds = %for.cond, %for.inc
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%1 = load i32, i32* @a, align 4
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%cmp2 = icmp slt i32 %1, 1
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br i1 %cmp2, label %for.body3, label %for.inc5
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for.body3: ; preds = %for.cond1
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%tobool = icmp ne i32 %1, 0
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br i1 %tobool, label %if.then, label %for.inc
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if.then: ; preds = %for.body3
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%inc = add nsw i32 %1, 1
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store i32 %inc, i32* @a, align 4
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br label %for.inc
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for.inc: ; preds = %for.body3, %if.then
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%2 = load i32, i32* @a, align 4
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%inc4 = add nsw i32 %2, 1
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store i32 %inc4, i32* @a, align 4
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br label %for.cond1
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for.inc5: ; preds = %for.cond1
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%inc6 = add nsw i32 %1, 1
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store i32 %inc6, i32* @a, align 4
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br label %for.cond
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for.end7: ; preds = %for.cond
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ret i32 %0
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}
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