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bc72c8f0d8
This patch modifies SelectionDAGBuilder to construct SDNodes with associated NoSignedWrap, NoUnsignedWrap and Exact flags coming from IR BinaryOperator instructions. Added a new SDNode type called 'BinaryWithFlagsSDNode' to allow accessing nsw/nuw/exact flags during codegen. Patch by Marcello Maggioni. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210467 91177308-0d34-0410-b5e6-96231b3b80d8
21 lines
807 B
LLVM
21 lines
807 B
LLVM
; RUN: llc < %s -march=x86-64 | FileCheck %s
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; CHECK: addl
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; The two additions are the same , but have different flags.
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; In theory this code should never be generated by the frontend, but this
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; tries to test that two identical instructions with two different flags
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; actually generate two different nodes.
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;
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; Normally the combiner would see this condition without the flags
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; and optimize the result of the sub into a register clear
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; (the final result would be 0). With the different flags though the combiner
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; needs to keep the add + sub nodes, because the two nodes result as different
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; nodes and so cannot assume that the subtraction of the two nodes
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; generates 0 as result
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define i32 @foo(i32 %a, i32 %b) {
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%1 = add i32 %a, %b
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%2 = add nsw i32 %a, %b
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%3 = sub i32 %1, %2
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ret i32 %3
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}
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