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ac6f04f1d5
This is a reapplication of r221171, but we only perform the transformation on expressions which include a multiplication. We do not transform rem/div operations as this doesn't appear to be safe in all cases. llvm-svn: 221721
35 lines
772 B
LLVM
35 lines
772 B
LLVM
; RUN: opt < %s -reassociate -dce -S | FileCheck %s
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; PR12985
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; Verify the nsw flags are preserved when converting shl to mul.
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; CHECK-LABEL: @shl_to_mul_nsw(
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; CHECK: %mul = mul i32 %i, -2147483648
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; CHECK: add i32 %mul, 1
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define i32 @shl_to_mul_nsw(i32 %i) {
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entry:
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%mul = shl nsw i32 %i, 31
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%mul2 = add i32 %mul, 1
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ret i32 %mul2
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}
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; CHECK-LABEL: @shl_to_mul_nuw(
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; CHECK: %mul = mul nuw i32 %i, 4
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; CHECK: add i32 %mul, 1
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define i32 @shl_to_mul_nuw(i32 %i) {
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entry:
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%mul = shl nuw i32 %i, 2
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%mul2 = add i32 %mul, 1
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ret i32 %mul2
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}
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; CHECK-LABEL: @shl_to_mul_nuw_nsw(
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; CHECK: %mul = mul nuw nsw i32 %i, 4
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; CHECK: add i32 %mul, 1
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define i32 @shl_to_mul_nuw_nsw(i32 %i) {
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entry:
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%mul = shl nuw nsw i32 %i, 2
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%mul2 = add i32 %mul, 1
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ret i32 %mul2
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}
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