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Don't fold and's into test instructions if they have multiple uses.

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This compiles test-nofold.ll into:

_test:
	movl	$15, %ecx
	andl	4(%esp), %ecx
	testl	%ecx, %ecx
	movl	$42, %eax
	cmove	%ecx, %eax
	ret

instead of:
_test:
	movl	4(%esp), %eax
	movl	%eax, %ecx
	andl	$15, %ecx
	testl	$15, %eax
	movl	$42, %eax
	cmove	%ecx, %eax
	ret



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47330 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2008-02-19 17:37:35 +00:00
parent 22c31769fb
commit ce2bcc8839
2 changed files with 41 additions and 6 deletions
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18
lib/Target/X86/X86InstrInfo.td
View File

@ -245,6 +245,12 @@ def extloadi16i8 : PatFrag<(ops node:$ptr), (i16 (extloadi8 node:$ptr))>;
def extloadi32i8 : PatFrag<(ops node:$ptr), (i32 (extloadi8 node:$ptr))>;
def extloadi32i16 : PatFrag<(ops node:$ptr), (i32 (extloadi16 node:$ptr))>;
// An 'and' node with a single use.
def and_su : PatFrag<(ops node:$lhs, node:$rhs), (and node:$lhs, node:$rhs), [{
return N->hasOneUse();
}]>;
//===----------------------------------------------------------------------===//
// Instruction list...
//
@ -2078,16 +2084,16 @@ let Defs = [EFLAGS] in {
let isCommutable = 1 in { // TEST X, Y --> TEST Y, X
def TEST8rr : I<0x84, MRMDestReg, (outs), (ins GR8:$src1, GR8:$src2),
"test{b}\t{$src2, $src1|$src1, $src2}",
[(X86cmp (and GR8:$src1, GR8:$src2), 0),
[(X86cmp (and_su GR8:$src1, GR8:$src2), 0),
(implicit EFLAGS)]>;
def TEST16rr : I<0x85, MRMDestReg, (outs), (ins GR16:$src1, GR16:$src2),
"test{w}\t{$src2, $src1|$src1, $src2}",
[(X86cmp (and GR16:$src1, GR16:$src2), 0),
[(X86cmp (and_su GR16:$src1, GR16:$src2), 0),
(implicit EFLAGS)]>,
OpSize;
def TEST32rr : I<0x85, MRMDestReg, (outs), (ins GR32:$src1, GR32:$src2),
"test{l}\t{$src2, $src1|$src1, $src2}",
[(X86cmp (and GR32:$src1, GR32:$src2), 0),
[(X86cmp (and_su GR32:$src1, GR32:$src2), 0),
(implicit EFLAGS)]>;
}
@ -2107,17 +2113,17 @@ def TEST32rm : I<0x85, MRMSrcMem, (outs), (ins GR32:$src1, i32mem:$src2),
def TEST8ri : Ii8 <0xF6, MRM0r, // flags = GR8 & imm8
(outs), (ins GR8:$src1, i8imm:$src2),
"test{b}\t{$src2, $src1|$src1, $src2}",
[(X86cmp (and GR8:$src1, imm:$src2), 0),
[(X86cmp (and_su GR8:$src1, imm:$src2), 0),
(implicit EFLAGS)]>;
def TEST16ri : Ii16<0xF7, MRM0r, // flags = GR16 & imm16
(outs), (ins GR16:$src1, i16imm:$src2),
"test{w}\t{$src2, $src1|$src1, $src2}",
[(X86cmp (and GR16:$src1, imm:$src2), 0),
[(X86cmp (and_su GR16:$src1, imm:$src2), 0),
(implicit EFLAGS)]>, OpSize;
def TEST32ri : Ii32<0xF7, MRM0r, // flags = GR32 & imm32
(outs), (ins GR32:$src1, i32imm:$src2),
"test{l}\t{$src2, $src1|$src1, $src2}",
[(X86cmp (and GR32:$src1, imm:$src2), 0),
[(X86cmp (and_su GR32:$src1, imm:$src2), 0),
(implicit EFLAGS)]>;
def TEST8mi : Ii8 <0xF6, MRM0m, // flags = [mem8] & imm8

29
test/CodeGen/X86/test-nofold.ll Normal file
View File

@ -0,0 +1,29 @@
; RUN: llvm-as < %s | llc -march=x86 -mcpu=yonah | grep {testl.*%e.x.*%e.x}
; rdar://5752025
; We don't want to fold the and into the test, because the and clobbers its
; input forcing a copy. We want:
; movl $15, %ecx
; andl 4(%esp), %ecx
; testl %ecx, %ecx
; movl $42, %eax
; cmove %ecx, %eax
; ret
;
; Not:
; movl 4(%esp), %eax
; movl %eax, %ecx
; andl $15, %ecx
; testl $15, %eax
; movl $42, %eax
; cmove %ecx, %eax
; ret
define i32 @t1(i32 %X) nounwind {
entry:
%tmp2 = and i32 %X, 15 ; <i32> [#uses=2]
%tmp4 = icmp eq i32 %tmp2, 0 ; <i1> [#uses=1]
%retval = select i1 %tmp4, i32 %tmp2, i32 42 ; <i32> [#uses=1]
ret i32 %retval
}