AMDGPU: Don't fold copies to physregs

In a future patch, this will help cleanup m0 handling.

The register coalescer handles copies from a register that
materializes an immediate, but doesn't handle move immediates
itself. The virtual register uses will often be allocated to the same
register, so there end up being no real copy.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@374257 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/AMDGPU/SIFoldOperands.cpp b/lib/Target/AMDGPU/SIFoldOperands.cpp
index 1f8b744155d6801c9ae9d1d170f59043c36212a7..698bcbdb9832c38841d23fe054bd02b204fc1900 100644 (file)
--- a/lib/Target/AMDGPU/SIFoldOperands.cpp
+++ b/lib/Target/AMDGPU/SIFoldOperands.cpp
@@ -581,13 +581,17 @@ void SIFoldOperands::foldOperand(
 
   if (FoldingImmLike && UseMI->isCopy()) {
     Register DestReg = UseMI->getOperand(0).getReg();
-    const TargetRegisterClass *DestRC = Register::isVirtualRegister(DestReg)
-                                            ? MRI->getRegClass(DestReg)
-                                            : TRI->getPhysRegClass(DestReg);
+
+    // Don't fold into a copy to a physical register. Doing so would interfere
+    // with the register coalescer's logic which would avoid redundant
+    // initalizations.
+    if (DestReg.isPhysical())
+      return;
+
+    const TargetRegisterClass *DestRC =  MRI->getRegClass(DestReg);
 
     Register SrcReg = UseMI->getOperand(1).getReg();
-    if (Register::isVirtualRegister(DestReg) &&
-        Register::isVirtualRegister(SrcReg)) {
+    if (SrcReg.isVirtual()) { // XXX - This can be an assert?
       const TargetRegisterClass * SrcRC = MRI->getRegClass(SrcReg);
       if (TRI->isSGPRClass(SrcRC) && TRI->hasVectorRegisters(DestRC)) {
         MachineRegisterInfo::use_iterator NextUse;

diff --git a/test/CodeGen/AMDGPU/stack-pointer-offset-relative-frameindex.ll b/test/CodeGen/AMDGPU/stack-pointer-offset-relative-frameindex.ll
index 7a2085fa36153351c1119f829fdd405e5d94268d..00ae166a6ce51a0a22fd8b42c6eb8408cf92c528 100644 (file)
--- a/test/CodeGen/AMDGPU/stack-pointer-offset-relative-frameindex.ll
+++ b/test/CodeGen/AMDGPU/stack-pointer-offset-relative-frameindex.ll
@@ -14,8 +14,8 @@ define amdgpu_kernel void @kernel_background_evaluate(float addrspace(5)* %kg, <
 ; GCN-NEXT:    s_mov_b64 s[0:1], s[36:37]
 ; GCN-NEXT:    v_mov_b32_e32 v1, 0x2000
 ; GCN-NEXT:    v_mov_b32_e32 v2, 0x4000
-; GCN-NEXT:    s_mov_b64 s[2:3], s[38:39]
 ; GCN-NEXT:    v_mov_b32_e32 v3, 0
+; GCN-NEXT:    s_mov_b64 s[2:3], s[38:39]
 ; GCN-NEXT:    v_mov_b32_e32 v4, 0x400000
 ; GCN-NEXT:    s_add_u32 s32, s33, 0xc0000
 ; GCN-NEXT:    v_add_nc_u32_e64 v32, 4, 0x4000