[X86] Make WRPKRU/RDPKRU pass -verify-machineinstrs

The original implementation attempted to zero registers using
XOR %foo, %foo.  This is problematic because it constitutes a
read-modify-write of a register which might not be defined.

Instead, use MOV32r0 to avoid these problems; expandPostRAPseudo does
the right thing here.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@274024 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 0c969c93c619ce92a92f1d92e788a1affd46dca6..859c27afe449de04f9d9be6f92172ad88caa1d0a 100644 (file)
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -22547,13 +22547,11 @@ static MachineBasicBlock *emitWRPKRU(MachineInstr *MI, MachineBasicBlock *BB,
   BuildMI(*BB, MI, dl, TII->get(TargetOpcode::COPY), X86::EAX)
                            .addReg(MI->getOperand(0).getReg());
   // insert zero to ECX
-  BuildMI(*BB, MI, dl, TII->get(X86::XOR32rr), X86::ECX)
-                           .addReg(X86::ECX)
-                           .addReg(X86::ECX);
+  BuildMI(*BB, MI, dl, TII->get(X86::MOV32r0), X86::ECX);
+
   // insert zero to EDX
-  BuildMI(*BB, MI, dl, TII->get(X86::XOR32rr), X86::EDX)
-                           .addReg(X86::EDX)
-                           .addReg(X86::EDX);
+  BuildMI(*BB, MI, dl, TII->get(X86::MOV32r0), X86::EDX);
+
   // insert WRPKRU instruction
   BuildMI(*BB, MI, dl, TII->get(X86::WRPKRUr));
 
@@ -22567,9 +22565,8 @@ static MachineBasicBlock *emitRDPKRU(MachineInstr *MI, MachineBasicBlock *BB,
   const TargetInstrInfo *TII = Subtarget.getInstrInfo();
 
   // insert zero to ECX
-  BuildMI(*BB, MI, dl, TII->get(X86::XOR32rr), X86::ECX)
-                           .addReg(X86::ECX)
-                           .addReg(X86::ECX);
+  BuildMI(*BB, MI, dl, TII->get(X86::MOV32r0), X86::ECX);
+
   // insert RDPKRU instruction
   BuildMI(*BB, MI, dl, TII->get(X86::RDPKRUr));
   BuildMI(*BB, MI, dl, TII->get(TargetOpcode::COPY), MI->getOperand(0).getReg())

diff --git a/test/CodeGen/X86/pku.ll b/test/CodeGen/X86/pku.ll
index 8568cf43abc05647028f02594aa7b707c06d561d..79b8c474ade0623d31098989e225b4d61cb6b970 100644 (file)
--- a/test/CodeGen/X86/pku.ll
+++ b/test/CodeGen/X86/pku.ll
@@ -1,4 +1,4 @@
-; RUN: llc < %s -mtriple=x86_64-apple-darwin -mcpu=knl --show-mc-encoding| FileCheck %s
+; RUN: llc < %s -mtriple=x86_64-apple-darwin -mcpu=knl --show-mc-encoding -verify-machineinstrs | FileCheck %s
 declare i32 @llvm.x86.rdpkru()
 declare void @llvm.x86.wrpkru(i32)