From: Chris Lattner <sabre@nondot.org>
Date: Tue, 19 Feb 2008 17:37:35 +0000 (+0000)
Subject: Don't fold and's into test instructions if they have multiple uses.
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=ce2bcc8839834b5f5c5efbf269f547aafb638df4;p=oota-llvm.git

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



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47330 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Target/X86/X86InstrInfo.td b/lib/Target/X86/X86InstrInfo.td
index f40847f1e47..4482da7d4b1 100644
--- a/lib/Target/X86/X86InstrInfo.td
+++ b/lib/Target/X86/X86InstrInfo.td
@@ -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
diff --git a/test/CodeGen/X86/test-nofold.ll b/test/CodeGen/X86/test-nofold.ll
new file mode 100644
index 00000000000..a24a9a0940a
--- /dev/null
+++ b/test/CodeGen/X86/test-nofold.ll
@@ -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
+}
+