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Fix a minor bug in two-address pass. It was missing a commute opportunity.

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regB = move RCX
regA = op regB, regC
RAX  = move regA
where both regB and regC are killed. If regB is constrainted to non-compatible
physical registers but regC is not constrainted at all, then it's better to
commute the instruction.
       movl    %edi, %eax
       shlq    $32, %rcx
       leaq    (%rcx,%rax), %rax
=>
       movl    %edi, %eax
       shlq    $32, %rcx
       orq     %rcx, %rax
rdar://8762995

llvm-svn: 121793
This commit is contained in:
Evan Cheng 2010-12-14 21:34:53 +00:00
parent 70721628b4
commit 7e96e67d98
2 changed files with 45 additions and 6 deletions
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3
lib/CodeGen/TwoAddressInstructionPass.cpp
View File

@ -554,7 +554,8 @@ TwoAddressInstructionPass::isProfitableToCommute(unsigned regB, unsigned regC,
unsigned ToRegB = getMappedReg(regB, DstRegMap);
unsigned ToRegC = getMappedReg(regC, DstRegMap);
if (!regsAreCompatible(FromRegB, ToRegB, TRI) &&
(regsAreCompatible(FromRegB, ToRegC, TRI) ||
((!FromRegC && !ToRegC) ||
regsAreCompatible(FromRegB, ToRegC, TRI) ||
regsAreCompatible(FromRegC, ToRegB, TRI)))
return true;

48
test/CodeGen/X86/commute-two-addr.ll
View File

@ -2,24 +2,62 @@
; insertion of register-register copies.
; Make sure there are only 3 mov's for each testcase
; RUN: llc < %s -march=x86 -x86-asm-syntax=intel | \
; RUN: grep {\\\<mov\\\>} | count 6
; RUN: llc < %s -mtriple=i686-pc-linux-gnu | FileCheck %s -check-prefix=LINUX
; RUN: llc < %s -mtriple=x86_64-apple-darwin | FileCheck %s -check-prefix=DARWIN
target triple = "i686-pc-linux-gnu"
@G = external global i32 ; <i32*> [#uses=2]
declare void @ext(i32)
define i32 @add_test(i32 %X, i32 %Y) {
define i32 @t1(i32 %X, i32 %Y) nounwind {
; LINUX: t1:
; LINUX: movl 4(%esp), %eax
; LINUX: movl 8(%esp), %ecx
; LINUX: addl %eax, %ecx
; LINUX: movl %ecx, G
%Z = add i32 %X, %Y ; <i32> [#uses=1]
store i32 %Z, i32* @G
ret i32 %X
}
define i32 @xor_test(i32 %X, i32 %Y) {
define i32 @t2(i32 %X, i32 %Y) nounwind {
; LINUX: t2:
; LINUX: movl 4(%esp), %eax
; LINUX: movl 8(%esp), %ecx
; LINUX: xorl %eax, %ecx
; LINUX: movl %ecx, G
%Z = xor i32 %X, %Y ; <i32> [#uses=1]
store i32 %Z, i32* @G
ret i32 %X
}
; rdar://8762995
%0 = type { i64, i32 }
define %0 @t3(i32 %lb, i8 zeroext %has_lb, i8 zeroext %lb_inclusive, i32 %ub, i8 zeroext %has_ub, i8 zeroext %ub_inclusive) nounwind {
entry:
; DARWIN: t3:
; DARWIN: shlq $32, %rcx
; DARWIN-NOT: leaq
; DARWIN: orq %rcx, %rax
; DARWIN-NOT: mov
; DARWIN: shll $16
%tmp21 = zext i32 %lb to i64
%tmp23 = zext i32 %ub to i64
%tmp24 = shl i64 %tmp23, 32
%ins26 = or i64 %tmp24, %tmp21
%tmp28 = zext i8 %has_lb to i32
%tmp33 = zext i8 %has_ub to i32
%tmp34 = shl i32 %tmp33, 8
%tmp38 = zext i8 %lb_inclusive to i32
%tmp39 = shl i32 %tmp38, 16
%tmp43 = zext i8 %ub_inclusive to i32
%tmp44 = shl i32 %tmp43, 24
%ins31 = or i32 %tmp39, %tmp28
%ins36 = or i32 %ins31, %tmp34
%ins46 = or i32 %ins36, %tmp44
%tmp16 = insertvalue %0 undef, i64 %ins26, 0
%tmp19 = insertvalue %0 %tmp16, i32 %ins46, 1
ret %0 %tmp19
}