mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-07-21 02:29:22 +00:00
fe08a38a2c
This commit teaches the X86 backend to create the same X86 instructions when it lowers an sadd/ssub with overflow intrinsic and a conditional branch that uses that overflow result. This allows SelectionDAG to recognize and remove one of the redundant operations. This fixes <rdar://problem/15874016> and <rdar://problem/15661073>. Reviewed by Nadav git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199976 91177308-0d34-0410-b5e6-96231b3b80d8
35 lines
805 B
LLVM
35 lines
805 B
LLVM
; RUN: llc < %s -mtriple=x86_64-apple-darwin | FileCheck %s
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define void @redundant_add(i64 %n) {
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; Check that we don't create two additions for the sadd.with.overflow.
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; CHECK-LABEL: redundant_add
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; CHECK-NOT: leaq
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; CHECK-NOT: addq
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; CHECK: incq
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; CHECK-NEXT: jno
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entry:
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br label %exit_check
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exit_check:
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%i = phi i64 [ 0, %entry ], [ %i.next, %loop ]
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%c = icmp slt i64 %i, %n
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br i1 %c, label %loop, label %exit
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loop:
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%i.o = tail call { i64, i1 } @llvm.sadd.with.overflow.i64(i64 %i, i64 1)
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%i.next = extractvalue { i64, i1 } %i.o, 0
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%o = extractvalue { i64, i1 } %i.o, 1
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br i1 %o, label %overflow, label %exit_check
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exit:
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ret void
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overflow:
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tail call void @llvm.trap()
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unreachable
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}
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declare { i64, i1 } @llvm.sadd.with.overflow.i64(i64, i64)
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declare void @llvm.trap()
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