[llvm-commits] [llvm] r47330 - in /llvm/trunk: lib/Target/X86/X86InstrInfo.td test/CodeGen/X86/test-nofold.ll

[Chris Lattner]

Author: lattner
Date: Tue Feb 19 11:37:35 2008
New Revision: 47330

URL: http://llvm.org/viewvc/llvm-project?rev=47330&view=rev
Log:
Don't fold and's into test instructions if they have multiple uses.
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


Added:
    llvm/trunk/test/CodeGen/X86/test-nofold.ll
Modified:
    llvm/trunk/lib/Target/X86/X86InstrInfo.td

Modified: llvm/trunk/lib/Target/X86/X86InstrInfo.td
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86InstrInfo.td?rev=47330&r1=47329&r2=47330&view=diff

==============================================================================
--- llvm/trunk/lib/Target/X86/X86InstrInfo.td (original)
+++ llvm/trunk/lib/Target/X86/X86InstrInfo.td Tue Feb 19 11:37:35 2008
@@ -245,6 +245,12 @@
 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 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 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

Added: llvm/trunk/test/CodeGen/X86/test-nofold.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/test-nofold.ll?rev=47330&view=auto

==============================================================================
--- llvm/trunk/test/CodeGen/X86/test-nofold.ll (added)
+++ llvm/trunk/test/CodeGen/X86/test-nofold.ll Tue Feb 19 11:37:35 2008
@@ -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
+}
+