From 4a9dd7c39b197fc13eeb1d27ba97ecedc7c6602a Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper@intel.com>
Date: Tue, 5 Mar 2019 18:37:41 +0000
Subject: [PATCH] [X86] Enable 8-bit SHL to convert to LEA

Differential Revision: https://reviews.llvm.org/D58870

llvm-svn: 355425
---
 llvm/lib/Target/X86/X86InstrInfo.cpp       |  4 ++++
 llvm/lib/Target/X86/X86InstrShiftRotate.td |  2 +-
 llvm/test/CodeGen/X86/fast-isel-shift.ll   |  4 ++--
 llvm/test/CodeGen/X86/mul-constant-i8.ll   | 12 ++++++------
 4 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/llvm/lib/Target/X86/X86InstrInfo.cpp b/llvm/lib/Target/X86/X86InstrInfo.cpp
index 01b1740..435e487 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.cpp
+++ b/llvm/lib/Target/X86/X86InstrInfo.cpp
@@ -755,6 +755,7 @@ MachineInstr *X86InstrInfo::convertToThreeAddressWithLEA(
       BuildMI(*MFI, MBBI, MI.getDebugLoc(), get(Opcode), OutRegLEA);
   switch (MIOpc) {
   default: llvm_unreachable("Unreachable!");
+  case X86::SHL8ri:
   case X86::SHL16ri: {
     unsigned ShAmt = MI.getOperand(2).getImm();
     MIB.addReg(0).addImm(1ULL << ShAmt)
@@ -918,6 +919,9 @@ X86InstrInfo::convertToThreeAddress(MachineFunction::iterator &MFI,
 
     break;
   }
+  case X86::SHL8ri:
+    Is8BitOp = true;
+    LLVM_FALLTHROUGH;
   case X86::SHL16ri: {
     assert(MI.getNumOperands() >= 3 && "Unknown shift instruction!");
     unsigned ShAmt = getTruncatedShiftCount(MI, 2);
diff --git a/llvm/lib/Target/X86/X86InstrShiftRotate.td b/llvm/lib/Target/X86/X86InstrShiftRotate.td
index 21a20c1..0853056 100644
--- a/llvm/lib/Target/X86/X86InstrShiftRotate.td
+++ b/llvm/lib/Target/X86/X86InstrShiftRotate.td
@@ -30,11 +30,11 @@ def SHL64rCL : RI<0xD3, MRM4r, (outs GR64:$dst), (ins GR64:$src1),
                   [(set GR64:$dst, (shl GR64:$src1, CL))]>;
 } // Uses = [CL], SchedRW
 
+let isConvertibleToThreeAddress = 1 in {   // Can transform into LEA.
 def SHL8ri   : Ii8<0xC0, MRM4r, (outs GR8 :$dst), (ins GR8 :$src1, u8imm:$src2),
                    "shl{b}\t{$src2, $dst|$dst, $src2}",
                    [(set GR8:$dst, (shl GR8:$src1, (i8 imm:$src2)))]>;
 
-let isConvertibleToThreeAddress = 1 in {   // Can transform into LEA.
 def SHL16ri  : Ii8<0xC1, MRM4r, (outs GR16:$dst), (ins GR16:$src1, u8imm:$src2),
                    "shl{w}\t{$src2, $dst|$dst, $src2}",
                    [(set GR16:$dst, (shl GR16:$src1, (i8 imm:$src2)))]>,
diff --git a/llvm/test/CodeGen/X86/fast-isel-shift.ll b/llvm/test/CodeGen/X86/fast-isel-shift.ll
index 2aff7cf..243bb4ad 100644
--- a/llvm/test/CodeGen/X86/fast-isel-shift.ll
+++ b/llvm/test/CodeGen/X86/fast-isel-shift.ll
@@ -157,8 +157,8 @@ define i64 @ashr_i64(i64 %a, i64 %b) {
 define i8 @shl_imm1_i8(i8 %a) {
 ; CHECK-LABEL: shl_imm1_i8:
 ; CHECK:       ## %bb.0:
-; CHECK-NEXT:    movl %edi, %eax
-; CHECK-NEXT:    shlb $1, %al
+; CHECK-NEXT:    ## kill: def $edi killed $edi def $rdi
+; CHECK-NEXT:    leal (,%rdi,2), %eax
 ; CHECK-NEXT:    ## kill: def $al killed $al killed $eax
 ; CHECK-NEXT:    retq
   %c = shl i8 %a, 1
diff --git a/llvm/test/CodeGen/X86/mul-constant-i8.ll b/llvm/test/CodeGen/X86/mul-constant-i8.ll
index 43afd24..5a33888 100644
--- a/llvm/test/CodeGen/X86/mul-constant-i8.ll
+++ b/llvm/test/CodeGen/X86/mul-constant-i8.ll
@@ -36,8 +36,8 @@ define i8 @test_mul_by_3(i8 %x) {
 define i8 @test_mul_by_4(i8 %x) {
 ; X64-LABEL: test_mul_by_4:
 ; X64:       # %bb.0:
-; X64-NEXT:    movl %edi, %eax
-; X64-NEXT:    shlb $2, %al
+; X64-NEXT:    # kill: def $edi killed $edi def $rdi
+; X64-NEXT:    leal (,%rdi,4), %eax
 ; X64-NEXT:    # kill: def $al killed $al killed $eax
 ; X64-NEXT:    retq
   %m = mul i8 %x, 4
@@ -82,8 +82,8 @@ define i8 @test_mul_by_7(i8 %x) {
 define i8 @test_mul_by_8(i8 %x) {
 ; X64-LABEL: test_mul_by_8:
 ; X64:       # %bb.0:
-; X64-NEXT:    movl %edi, %eax
-; X64-NEXT:    shlb $3, %al
+; X64-NEXT:    # kill: def $edi killed $edi def $rdi
+; X64-NEXT:    leal (,%rdi,8), %eax
 ; X64-NEXT:    # kill: def $al killed $al killed $eax
 ; X64-NEXT:    retq
   %m = mul i8 %x, 8
@@ -449,8 +449,8 @@ define i8 @test_mul_by_73(i8 %x) {
 define i8 @test_mul_by_520(i8 %x) {
 ; X64-LABEL: test_mul_by_520:
 ; X64:       # %bb.0:
-; X64-NEXT:    movl %edi, %eax
-; X64-NEXT:    shlb $3, %al
+; X64-NEXT:    # kill: def $edi killed $edi def $rdi
+; X64-NEXT:    leal (,%rdi,8), %eax
 ; X64-NEXT:    # kill: def $al killed $al killed $eax
 ; X64-NEXT:    retq
   %m = mul i8 %x, 520
-- 
2.7.4