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a1a323c637
TwoAddressInstructionPass stops after a successful commuting but 3 Addr
conversion might be good for some cases.
Consider:
int foo(int a, int b) {
return a + b;
}
Before this commit, we emit:
addl %esi, %edi
movl %edi, %eax
ret
After this commit, we try 3 Addr conversion:
leal (%rsi,%rdi), %eax
ret
Patch by Volkan Keles <vkeles@apple.com>!
Differential Revision: http://reviews.llvm.org/D10851
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241206 91177308-0d34-0410-b5e6-96231b3b80d8
47 lines
1.2 KiB
LLVM
47 lines
1.2 KiB
LLVM
;; X's live range extends beyond the shift, so the register allocator
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;; cannot coalesce it with Y. Because of this, a copy needs to be
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;; emitted before the shift to save the register value before it is
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;; clobbered. However, this copy is not needed if the register
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;; allocator turns the shift into an LEA. This also occurs for ADD.
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; Check that the shift gets turned into an LEA.
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; RUN: llc < %s -mcpu=generic -mtriple=x86_64-apple-darwin | FileCheck %s
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@G = external global i32
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define i32 @test1(i32 %X) nounwind {
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; CHECK-LABEL: test1:
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; CHECK-NOT: mov
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; CHECK: leal 1(%rdi)
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%Z = add i32 %X, 1
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store volatile i32 %Z, i32* @G
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ret i32 %X
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}
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; rdar://8977508
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; The second add should not be transformed to leal nor should it be
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; commutted (which would require inserting a copy).
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define i32 @test2(i32 inreg %a, i32 inreg %b, i32 %c, i32 %d) nounwind {
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entry:
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; CHECK-LABEL: test2:
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; CHECK: leal
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; CHECK-NEXT: addl
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; CHECK-NEXT: addl
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; CHECK-NEXT: ret
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%add = add i32 %b, %a
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%add3 = add i32 %add, %c
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%add5 = add i32 %add3, %d
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ret i32 %add5
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}
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; rdar://9002648
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define i64 @test3(i64 %x) nounwind readnone ssp {
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entry:
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; CHECK-LABEL: test3:
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; CHECK: leaq (%rdi,%rdi), %rax
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; CHECK-NOT: addq
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; CHECK-NEXT: ret
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%0 = shl i64 %x, 1
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ret i64 %0
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}
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