d2e5d3512b
In some cases StructurizeCFG inserts i1 xor instructions to invert predicates. Add a quick loop to clean these up afterwards if we can get away with modifying an existing compare instruction instead. (StructurizeCFG is generally run late in the pipeline so instcombine does not clean them up for us.) Differential Revision: https://reviews.llvm.org/D118623
55 lines
1.5 KiB
LLVM
55 lines
1.5 KiB
LLVM
; RUN: opt -S -structurizecfg %s | FileCheck %s
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; r321751 introduced a bug where control flow branching from if to exit was
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; not handled properly and instead ended up in an infinite loop.
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define void @bug36015(i32 %cmp0, i32 %count) {
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entry:
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br label %loop.outer
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loop.outer:
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%ctr.loop.outer = phi i32 [ 0, %entry ], [ %ctr.else, %else ]
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call void @foo(i32 0)
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br label %loop.inner
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loop.inner:
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%ctr.loop.inner = phi i32 [ %ctr.loop.outer, %loop.outer ], [ %ctr.if, %if ]
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call void @foo(i32 1)
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%cond.inner = icmp eq i32 %cmp0, %ctr.loop.inner
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br i1 %cond.inner, label %if, label %else
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; CHECK: if:
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; CHECK: %cond.if = icmp sge i32 %ctr.if, %count
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; CHECK: br label %Flow
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if:
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%ctr.if = add i32 %ctr.loop.inner, 1
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call void @foo(i32 2)
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%cond.if = icmp slt i32 %ctr.if, %count
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br i1 %cond.if, label %loop.inner, label %exit
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; CHECK: Flow:
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; CHECK: %1 = phi i1 [ %cond.if, %if ], [ true, %loop.inner ]
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; CHECK: %2 = phi i1 [ false, %if ], [ true, %loop.inner ]
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; CHECK: br i1 %1, label %Flow1, label %loop.inner
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; CHECK: Flow1:
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; CHECK: br i1 %2, label %else, label %Flow2
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; CHECK: else:
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; CHECK: %cond.else = icmp sge i32 %ctr.else, %count
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; CHECK: br label %Flow2
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else:
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%ctr.else = add i32 %ctr.loop.inner, 1
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call void @foo(i32 3)
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%cond.else = icmp slt i32 %ctr.else, %count
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br i1 %cond.else, label %loop.outer, label %exit
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; CHECK: Flow2:
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; CHECK: %4 = phi i1 [ %cond.else, %else ], [ true, %Flow1 ]
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; CHECK: br i1 %4, label %exit, label %loop.outer
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exit:
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ret void
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}
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declare void @foo(i32)
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