[FastISel][AArch64] Make use of the zero register when possible.

This change materializes now the value "0" from the zero register.
The zero register can be folded by several instruction, so no
materialization is need at all.

Fixes <rdar://problem/17924413>.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215591 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/AArch64/AArch64FastISel.cpp b/lib/Target/AArch64/AArch64FastISel.cpp
index 918e0cec0f9821f73be63e437e239ce98e85412c..316111d432ddf76de7354c229cb1cdcb65279a37 100644 (file)
--- a/lib/Target/AArch64/AArch64FastISel.cpp
+++ b/lib/Target/AArch64/AArch64FastISel.cpp
@@ -217,7 +217,19 @@ unsigned AArch64FastISel::TargetMaterializeAlloca(const AllocaInst *AI) {
 unsigned AArch64FastISel::AArch64MaterializeInt(const ConstantInt *CI, MVT VT) {
   if (VT > MVT::i64)
     return 0;
-  return FastEmit_i(VT, VT, ISD::Constant, CI->getZExtValue());
+
+  if (!CI->isZero())
+    return FastEmit_i(VT, VT, ISD::Constant, CI->getZExtValue());
+
+  // Create a copy from the zero register to materialize a "0" value.
+  const TargetRegisterClass *RC = (VT == MVT::i64) ? &AArch64::GPR64RegClass
+                                                   : &AArch64::GPR32RegClass;
+  unsigned ZeroReg = (VT == MVT::i64) ? AArch64::XZR : AArch64::WZR;
+  unsigned ResultReg = createResultReg(RC);
+  BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
+          TII.get(TargetOpcode::COPY), ResultReg)
+    .addReg(ZeroReg, getKillRegState(true));
+  return ResultReg;
 }
 
 unsigned AArch64FastISel::AArch64MaterializeFP(const ConstantFP *CFP, MVT VT) {

diff --git a/test/CodeGen/AArch64/arm64-fast-isel-call.ll b/test/CodeGen/AArch64/arm64-fast-isel-call.ll
index 302485837d49271e5cada2f102e535442b846a0f..34a227a9dc08bec812b5d6226a185ef11a31262a 100644 (file)
--- a/test/CodeGen/AArch64/arm64-fast-isel-call.ll
+++ b/test/CodeGen/AArch64/arm64-fast-isel-call.ll
@@ -42,7 +42,7 @@ entry:
 
 define i32 @sext_(i8 %a, i16 %b) nounwind {
 entry:
-; CHECK-LABEL: @sext_
+; CHECK-LABEL: sext_
 ; CHECK:       sxtb w0, w0
 ; CHECK:       sxth w1, w1
 ; CHECK:       bl _foo_sext_
@@ -54,7 +54,7 @@ declare void @foo_sext_(i8 %a, i16 %b)
 
 define i32 @zext_(i8 %a, i16 %b) nounwind {
 entry:
-; CHECK-LABEL: @zext_
+; CHECK-LABEL: zext_
 ; CHECK:       uxtb w0, w0
 ; CHECK:       uxth w1, w1
   call void @foo_zext_(i8 zeroext %a, i16 zeroext %b)
@@ -78,17 +78,18 @@ declare i32 @bar(i8 zeroext, i8 zeroext, i8 zeroext, i8 zeroext, i8 zeroext, i8
 ; Test materialization of integers.  Target-independent selector handles this.
 define i32 @t2() {
 entry:
-; CHECK-LABEL: @t2
-; CHECK:       movz x0, #0
+; CHECK-LABEL: t2
+; CHECK:       mov [[REG1:x[0-9]+]], xzr
 ; CHECK:       orr w1, wzr, #0xfffffff8
-; CHECK:       orr w[[REG:[0-9]+]], wzr, #0x3ff
-; CHECK:       orr w[[REG2:[0-9]+]], wzr, #0x2
-; CHECK:       movz w[[REG3:[0-9]+]], #0
-; CHECK:       orr w[[REG4:[0-9]+]], wzr, #0x1
-; CHECK:       uxth w2, w[[REG]]
-; CHECK:       sxtb w3, w[[REG2]]
-; CHECK:       and w4, w[[REG3]], #0x1
-; CHECK:       and w5, w[[REG4]], #0x1
+; CHECK:       orr [[REG2:w[0-9]+]], wzr, #0x3ff
+; CHECK:       orr [[REG3:w[0-9]+]], wzr, #0x2
+; CHECK:       mov [[REG4:w[0-9]+]], wzr
+; CHECK:       orr [[REG5:w[0-9]+]], wzr, #0x1
+; CHECK:       mov x0, [[REG1]]
+; CHECK:       uxth w2, [[REG2]]
+; CHECK:       sxtb w3, [[REG3]]
+; CHECK:       and w4, [[REG4]], #0x1
+; CHECK:       and w5, [[REG5]], #0x1
 ; CHECK:       bl _func2
   %call = call i32 @func2(i64 zeroext 0, i32 signext -8, i16 zeroext 1023, i8 signext -254, i1 zeroext 0, i1 zeroext 1)
   ret i32 0

diff --git a/test/CodeGen/AArch64/arm64-fast-isel-intrinsic.ll b/test/CodeGen/AArch64/arm64-fast-isel-intrinsic.ll
index 115298805ac15799be98433d1d95dab485b55edf..b16c899f4214e28b7389503af2f887fa2b475c48 100644 (file)
--- a/test/CodeGen/AArch64/arm64-fast-isel-intrinsic.ll
+++ b/test/CodeGen/AArch64/arm64-fast-isel-intrinsic.ll
@@ -7,7 +7,7 @@ define void @t1() {
 ; ARM64-LABEL: t1
 ; ARM64: adrp x8, _message@PAGE
 ; ARM64: add x0, x8, _message@PAGEOFF
-; ARM64: movz w9, #0
+; ARM64: mov w9, wzr
 ; ARM64: movz x2, #0x50
 ; ARM64: uxtb w1, w9
 ; ARM64: bl _memset

diff --git a/test/CodeGen/AArch64/arm64-fast-isel-store.ll b/test/CodeGen/AArch64/arm64-fast-isel-store.ll
new file mode 100644 (file)
index 0000000..362224f
--- /dev/null
+++ b/test/CodeGen/AArch64/arm64-fast-isel-store.ll
@@ -0,0 +1,30 @@
+; RUN: llc -mtriple=aarch64-unknown-unknown                             < %s | FileCheck %s
+; RUN: llc -mtriple=aarch64-unknown-unknown -fast-isel -fast-isel-abort < %s | FileCheck %s
+
+define void @store_i8(i8* %a) {
+; CHECK-LABEL: store_i8
+; CHECK: strb  wzr, [x0]
+  store i8 0, i8* %a
+  ret void
+}
+
+define void @store_i16(i16* %a) {
+; CHECK-LABEL: store_i16
+; CHECK: strh  wzr, [x0]
+  store i16 0, i16* %a
+  ret void
+}
+
+define void @store_i32(i32* %a) {
+; CHECK-LABEL: store_i32
+; CHECK: str  wzr, [x0]
+  store i32 0, i32* %a
+  ret void
+}
+
+define void @store_i64(i64* %a) {
+; CHECK-LABEL: store_i64
+; CHECK: str  xzr, [x0]
+  store i64 0, i64* %a
+  ret void
+}

diff --git a/test/CodeGen/AArch64/arm64-fast-isel.ll b/test/CodeGen/AArch64/arm64-fast-isel.ll
index 0194b3a6c2d4479cb7d670c7519596ec2b8dfb34..a71bdb2a3df4ca57af5916ce508842cf4b71e978 100644 (file)
--- a/test/CodeGen/AArch64/arm64-fast-isel.ll
+++ b/test/CodeGen/AArch64/arm64-fast-isel.ll
@@ -66,7 +66,7 @@ entry:
 define void @t4(i32 *%ptr) nounwind {
 entry:
 ; CHECK-LABEL: t4:
-; CHECK: movz w8, #0
+; CHECK: mov w8, wzr
 ; CHECK: stur w8, [x0, #-4]
 ; CHECK: ret
   %0 = getelementptr i32 *%ptr, i32 -1
@@ -77,7 +77,7 @@ entry:
 define void @t5(i32 *%ptr) nounwind {
 entry:
 ; CHECK-LABEL: t5:
-; CHECK: movz w8, #0
+; CHECK: mov w8, wzr
 ; CHECK: stur w8, [x0, #-256]
 ; CHECK: ret
   %0 = getelementptr i32 *%ptr, i32 -64