[X86] Form MUL_IMM for multiplies with 3/5/9 to encourage LEA formation over load...

Previously we only formed MUL_IMM when we split a constant. This blocked load folding on those cases. We should also form MUL_IMM for 3/5/9 to favor LEA over load folding.

Differential Revision: https://reviews.llvm.org/D46040

llvm-svn: 330850

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 1e6fb92..4d95a2c 100644 (file)
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -33225,9 +33225,14 @@ static SDValue combineMul(SDNode *N, SelectionDAG &DAG,
   if (!C)
     return SDValue();
   uint64_t MulAmt = C->getZExtValue();
-  if (isPowerOf2_64(MulAmt) || MulAmt == 3 || MulAmt == 5 || MulAmt == 9)
+  if (isPowerOf2_64(MulAmt))
     return SDValue();
 
+  SDLoc DL(N);
+  if (MulAmt == 3 || MulAmt == 5 || MulAmt == 9)
+    return DAG.getNode(X86ISD::MUL_IMM, DL, VT, N->getOperand(0),
+                       N->getOperand(1));
+
   uint64_t MulAmt1 = 0;
   uint64_t MulAmt2 = 0;
   if ((MulAmt % 9) == 0) {
@@ -33241,7 +33246,6 @@ static SDValue combineMul(SDNode *N, SelectionDAG &DAG,
     MulAmt2 = MulAmt / 3;
   }
 
-  SDLoc DL(N);
   SDValue NewMul;
   if (MulAmt2 &&
       (isPowerOf2_64(MulAmt2) || MulAmt2 == 3 || MulAmt2 == 5 || MulAmt2 == 9)){

diff --git a/llvm/test/CodeGen/X86/imul.ll b/llvm/test/CodeGen/X86/imul.ll
index 6896700..761484c 100644 (file)
--- a/llvm/test/CodeGen/X86/imul.ll
+++ b/llvm/test/CodeGen/X86/imul.ll
@@ -119,7 +119,8 @@ define i32 @mul3_32(i32 %A) {
 ;
 ; X86-LABEL: mul3_32:
 ; X86:       # %bb.0:
-; X86-NEXT:    imull $3, {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    leal (%eax,%eax,2), %eax
 ; X86-NEXT:    retl
 ; But why?!
     %mul = mul i32 %A, 3
@@ -134,9 +135,10 @@ define i64 @mul3_64(i64 %A) {
 ;
 ; X86-LABEL: mul3_64:
 ; X86:       # %bb.0:
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    leal (%eax,%eax,2), %ecx
 ; X86-NEXT:    movl $3, %eax
 ; X86-NEXT:    mull {{[0-9]+}}(%esp)
-; X86-NEXT:    imull $3, {{[0-9]+}}(%esp), %ecx
 ; X86-NEXT:    addl %ecx, %edx
 ; X86-NEXT:    retl
     %mul = mul i64 %A, 3

diff --git a/llvm/test/CodeGen/X86/mul-constant-i16.ll b/llvm/test/CodeGen/X86/mul-constant-i16.ll
index 60a69df..a90814c 100644 (file)
--- a/llvm/test/CodeGen/X86/mul-constant-i16.ll
+++ b/llvm/test/CodeGen/X86/mul-constant-i16.ll
@@ -37,7 +37,8 @@ define i16 @test_mul_by_2(i16 %x) {
 define i16 @test_mul_by_3(i16 %x) {
 ; X86-LABEL: test_mul_by_3:
 ; X86:       # %bb.0:
-; X86-NEXT:    imull $3, {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    leal (%eax,%eax,2), %eax
 ; X86-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-NEXT:    retl
 ;
@@ -72,7 +73,8 @@ define i16 @test_mul_by_4(i16 %x) {
 define i16 @test_mul_by_5(i16 %x) {
 ; X86-LABEL: test_mul_by_5:
 ; X86:       # %bb.0:
-; X86-NEXT:    imull $5, {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    leal (%eax,%eax,4), %eax
 ; X86-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-NEXT:    retl
 ;
@@ -147,7 +149,8 @@ define i16 @test_mul_by_8(i16 %x) {
 define i16 @test_mul_by_9(i16 %x) {
 ; X86-LABEL: test_mul_by_9:
 ; X86:       # %bb.0:
-; X86-NEXT:    imull $9, {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    leal (%eax,%eax,8), %eax
 ; X86-NEXT:    # kill: def $ax killed $ax killed $eax
 ; X86-NEXT:    retl
 ;

diff --git a/llvm/test/CodeGen/X86/mul-constant-i32.ll b/llvm/test/CodeGen/X86/mul-constant-i32.ll
index b3d2c07..6468c3f 100644 (file)
--- a/llvm/test/CodeGen/X86/mul-constant-i32.ll
+++ b/llvm/test/CodeGen/X86/mul-constant-i32.ll
@@ -107,7 +107,8 @@ define i32 @test_mul_by_2(i32 %x) {
 define i32 @test_mul_by_3(i32 %x) {
 ; X86-LABEL: test_mul_by_3:
 ; X86:       # %bb.0:
-; X86-NEXT:    imull $3, {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    leal (%eax,%eax,2), %eax
 ; X86-NEXT:    retl
 ;
 ; X64-HSW-LABEL: test_mul_by_3:
@@ -209,7 +210,8 @@ define i32 @test_mul_by_4(i32 %x) {
 define i32 @test_mul_by_5(i32 %x) {
 ; X86-LABEL: test_mul_by_5:
 ; X86:       # %bb.0:
-; X86-NEXT:    imull $5, {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    leal (%eax,%eax,4), %eax
 ; X86-NEXT:    retl
 ;
 ; X64-HSW-LABEL: test_mul_by_5:
@@ -415,7 +417,8 @@ define i32 @test_mul_by_8(i32 %x) {
 define i32 @test_mul_by_9(i32 %x) {
 ; X86-LABEL: test_mul_by_9:
 ; X86:       # %bb.0:
-; X86-NEXT:    imull $9, {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    leal (%eax,%eax,8), %eax
 ; X86-NEXT:    retl
 ;
 ; X64-HSW-LABEL: test_mul_by_9:

diff --git a/llvm/test/CodeGen/X86/mul-constant-i64.ll b/llvm/test/CodeGen/X86/mul-constant-i64.ll
index 538bc5c..6b860f1 100644 (file)
--- a/llvm/test/CodeGen/X86/mul-constant-i64.ll
+++ b/llvm/test/CodeGen/X86/mul-constant-i64.ll
@@ -107,9 +107,10 @@ define i64 @test_mul_by_2(i64 %x) {
 define i64 @test_mul_by_3(i64 %x) {
 ; X86-LABEL: test_mul_by_3:
 ; X86:       # %bb.0:
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    leal (%eax,%eax,2), %ecx
 ; X86-NEXT:    movl $3, %eax
 ; X86-NEXT:    mull {{[0-9]+}}(%esp)
-; X86-NEXT:    imull $3, {{[0-9]+}}(%esp), %ecx
 ; X86-NEXT:    addl %ecx, %edx
 ; X86-NEXT:    retl
 ;
@@ -207,9 +208,10 @@ define i64 @test_mul_by_4(i64 %x) {
 define i64 @test_mul_by_5(i64 %x) {
 ; X86-LABEL: test_mul_by_5:
 ; X86:       # %bb.0:
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    leal (%eax,%eax,4), %ecx
 ; X86-NEXT:    movl $5, %eax
 ; X86-NEXT:    mull {{[0-9]+}}(%esp)
-; X86-NEXT:    imull $5, {{[0-9]+}}(%esp), %ecx
 ; X86-NEXT:    addl %ecx, %edx
 ; X86-NEXT:    retl
 ;
@@ -416,9 +418,10 @@ define i64 @test_mul_by_8(i64 %x) {
 define i64 @test_mul_by_9(i64 %x) {
 ; X86-LABEL: test_mul_by_9:
 ; X86:       # %bb.0:
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    leal (%eax,%eax,8), %ecx
 ; X86-NEXT:    movl $9, %eax
 ; X86-NEXT:    mull {{[0-9]+}}(%esp)
-; X86-NEXT:    imull $9, {{[0-9]+}}(%esp), %ecx
 ; X86-NEXT:    addl %ecx, %edx
 ; X86-NEXT:    retl
 ;