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cf5240642b
When an overflow intrinsic is followed by a non-overflow instruction,
replace the latter with an extract. For example:
%sadd = tail call { i32, i1 } @llvm.sadd.with.overflow.i32(i32 %a, i32 %b)
%sadd3 = add i32 %a, %b
Here the add statement will be replaced by an extract.
When an overflow intrinsic follows a non-overflow instruction, a clone
of the intrinsic is inserted before the normal instruction, which makes
it the same as the previous case. Subsequent runs of GVN can then clean
up the duplicate instructions and insert the extract.
This fixes PR8817.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203553 91177308-0d34-0410-b5e6-96231b3b80d8
44 lines
1.4 KiB
LLVM
44 lines
1.4 KiB
LLVM
; RUN: opt -S -gvn < %s | FileCheck %s
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define i32 @sadd1(i32 %a, i32 %b) #0 {
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; CHECK-LABEL: @sadd1(
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entry:
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%sadd = tail call { i32, i1 } @llvm.sadd.with.overflow.i32(i32 %a, i32 %b)
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%cmp = extractvalue { i32, i1 } %sadd, 1
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br i1 %cmp, label %if.then, label %if.end
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if.then: ; preds = %entry
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ret i32 42
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if.end: ; preds = %entry
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%sadd3 = add i32 %a, %b
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ret i32 %sadd3
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; CHECK-NOT: add i32 %a, %b
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; CHECK: %sadd3.repl = extractvalue { i32, i1 } %sadd, 0
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; CHECK: ret i32 %sadd3.repl
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}
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define i32 @sadd2(i32 %a, i32 %b) #0 {
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entry:
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%sadd3 = add i32 %a, %b
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%sadd = tail call { i32, i1 } @llvm.sadd.with.overflow.i32(i32 %a, i32 %b)
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%cmp = extractvalue { i32, i1 } %sadd, 1
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br i1 %cmp, label %if.then, label %if.end
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; CHECK-NOT: %sadd3 = add i32 %a, %b
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; CHECK: %sadd.repl = tail call { i32, i1 } @llvm.sadd.with.overflow.i32(i32 %a, i32 %b)
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; CHECK-NOT: %sadd = tail call { i32, i1 } @llvm.sadd.with.overflow.i32(i32 %a, i32 %b)
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; CHECK: %sadd3.repl = extractvalue { i32, i1 } %sadd.repl, 0
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if.then: ; preds = %entry
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%sadd4 = add i32 %sadd3, 1
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ret i32 %sadd4
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; CHECK: %sadd4 = add i32 %sadd3.repl, 1
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if.end: ; preds = %entry
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ret i32 %sadd3
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; CHECK: ret i32 %sadd3.repl
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}
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declare { i32, i1 } @llvm.sadd.with.overflow.i32(i32, i32) nounwind readnone
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