[FastISel][X86] Use XOR to materialize the "0" value.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215594 91177308-0d34-0410-b5e6-96231b3b80d8

Author: ributzka

lib/Target/X86/X86FastISel.cpp

@@ -3107,6 +3107,29 @@ unsigned X86FastISel::X86MaterializeInt(const ConstantInt *CI, MVT VT) {
     return 0;
 
   uint64_t Imm = CI->getZExtValue();
+  if (Imm == 0) {
+    unsigned SrcReg = FastEmitInst_(X86::MOV32r0, &X86::GR32RegClass);
+    switch (VT.SimpleTy) {
+    default: llvm_unreachable("Unexpected value type");
+    case MVT::i1:
+    case MVT::i8:
+      return FastEmitInst_extractsubreg(MVT::i8, SrcReg, /*Kill=*/true,
+                                        X86::sub_8bit);
+    case MVT::i16:
+      return FastEmitInst_extractsubreg(MVT::i16, SrcReg, /*Kill=*/true,
+                                        X86::sub_16bit);
+    case MVT::i32:
+      return SrcReg;
+    case MVT::i64: {
+      unsigned ResultReg = createResultReg(&X86::GR64RegClass);
+      BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
+              TII.get(TargetOpcode::SUBREG_TO_REG), ResultReg)
+        .addImm(0).addReg(SrcReg).addImm(X86::sub_32bit);
+      return ResultReg;
+    }
+    }
+  }
+
   unsigned Opc = 0;
   switch (VT.SimpleTy) {
   default: llvm_unreachable("Unexpected value type");

test/CodeGen/X86/fast-isel-cmp-branch3.ll

@@ -351,7 +351,7 @@ bb1:
 define i32 @icmp_eq(i32 %x) {
 ; CHECK-LABEL: icmp_eq
 ; CHECK-NOT:   cmpl
-; CHECK:       movl $0, %eax
+; CHECK:       xorl %eax, %eax
   %1 = icmp eq i32 %x, %x
   br i1 %1, label %bb1, label %bb2
 bb2:
@@ -387,7 +387,7 @@ bb1:
 define i32 @icmp_uge(i32 %x) {
 ; CHECK-LABEL: icmp_uge
 ; CHECK-NOT:   cmpl
-; CHECK:       movl $0, %eax
+; CHECK:       xorl %eax, %eax
   %1 = icmp uge i32 %x, %x
   br i1 %1, label %bb1, label %bb2
 bb2:
@@ -411,7 +411,7 @@ bb1:
 define i32 @icmp_ule(i32 %x) {
 ; CHECK-LABEL: icmp_ule
 ; CHECK-NOT:   cmpl
-; CHECK:       movl $0, %eax
+; CHECK:       xorl %eax, %eax
   %1 = icmp ule i32 %x, %x
   br i1 %1, label %bb1, label %bb2
 bb2:
@@ -435,7 +435,7 @@ bb1:
 define i32 @icmp_sge(i32 %x) {
 ; CHECK-LABEL: icmp_sge
 ; CHECK-NOT:   cmpl
-; CHECK:       movl $0, %eax
+; CHECK:       xorl %eax, %eax
   %1 = icmp sge i32 %x, %x
   br i1 %1, label %bb1, label %bb2
 bb2:
@@ -459,7 +459,7 @@ bb1:
 define i32 @icmp_sle(i32 %x) {
 ; CHECK-LABEL: icmp_sle
 ; CHECK-NOT:   cmpl
-; CHECK:       movl $0, %eax
+; CHECK:       xorl %eax, %eax
   %1 = icmp sle i32 %x, %x
   br i1 %1, label %bb1, label %bb2
 bb2:

test/CodeGen/X86/fast-isel-mem.ll

@@ -36,11 +36,11 @@ entry:
 	store i32 (...)** getelementptr ([4 x i32 (...)*]* @LotsStuff, i32 0, i32 2), i32 (...)*** null, align 4
 	ret void
 ; CHECK: _t:
-; CHECK:	movl	$0, %eax
+; CHECK:	xorl    %eax, %eax
 ; CHECK:	movl	L_LotsStuff$non_lazy_ptr, %ecx
 
 ; ATOM: _t:
 ; ATOM:         movl    L_LotsStuff$non_lazy_ptr, %e{{..}}
-; ATOM:         movl    $0, %e{{..}}
+; ATOM:         xorl    %e{{..}}, %e{{..}}
 
 }

test/CodeGen/X86/fast-isel-x86-64.ll

@@ -144,7 +144,7 @@ if.end:                                           ; preds = %if.then, %entry
 ; CHECK-LABEL: test12:
 ; CHECK: testb	$1,
 ; CHECK-NEXT: je L
-; CHECK-NEXT: movl $0, %edi
+; CHECK-NEXT: xorl %edi, %edi
 ; CHECK-NEXT: callq
 }
 
@@ -154,7 +154,7 @@ define void @test13() nounwind {
   call void @test13f(i1 0)
   ret void
 ; CHECK-LABEL: test13:
-; CHECK: movl $0, %edi
+; CHECK: xorl %edi, %edi
 ; CHECK-NEXT: callq
 }
 
@@ -278,7 +278,7 @@ entry:
   call void @foo22(i32 3)
   ret void
 ; CHECK-LABEL: test22:
-; CHECK: movl	$0, %edi
+; CHECK: xorl	%edi, %edi
 ; CHECK: callq	_foo22
 ; CHECK: movl	$1, %edi
 ; CHECK: callq	_foo22

test/DebugInfo/X86/fission-ranges.ll

@@ -25,7 +25,7 @@
 ; if they've changed due to a bugfix, change in register allocation, etc.
 
 ; CHECK: [[A]]: Beginning address index: 2
-; CHECK-NEXT:                    Length: 199
+; CHECK-NEXT:                    Length: 190
 ; CHECK-NEXT:      Location description: 11 00
 ; CHECK-NEXT: {{^$}}
 ; CHECK-NEXT:   Beginning address index: 3