AMDGPU: Relax SGPR asm constraint register class

s should be SReg_32 to be as general as possible. This can avoid a copy
from m0.

llvm-svn: 280154

2 files changed, 11 insertions, 1 deletions

diff --git a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
index 28d9322a471..b79bdeadef3 100644
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -3751,7 +3751,7 @@ SITargetLowering::getRegForInlineAsmConstraint(const TargetRegisterInfo *TRI,
       default:
         return std::make_pair(0U, nullptr);
       case 32:
-        return std::make_pair(0U, &AMDGPU::SGPR_32RegClass);
+        return std::make_pair(0U, &AMDGPU::SReg_32RegClass);
       case 64:
         return std::make_pair(0U, &AMDGPU::SGPR_64RegClass);
       case 128:
diff --git a/llvm/test/CodeGen/AMDGPU/inline-constraints.ll b/llvm/test/CodeGen/AMDGPU/inline-constraints.ll
index 78868710c6a..7282e89e85b 100644
--- a/llvm/test/CodeGen/AMDGPU/inline-constraints.ll
+++ b/llvm/test/CodeGen/AMDGPU/inline-constraints.ll
@@ -21,3 +21,13 @@ entry:
   %s256 =  tail call <8 x i32> asm sideeffect "s_load_dwordx8 $0, $1", "=s,s"(i32 addrspace(1)* %ptr)
   ret void
 }
+
+; GCN-LABEL: {{^}}inline_sreg_constraint_m0:
+; GCN: s_mov_b32 m0, -1
+; GCN-NOT: s_mov_b32 s{{[0-9]+}}, m0
+; GCN: ; use m0
+define void @inline_sreg_constraint_m0(i32 addrspace(1)* %ptr) {
+  %m0 = tail call i32 asm sideeffect "s_mov_b32 m0, -1", "={M0}"()
+  tail call void asm sideeffect "; use $0", "s"(i32 %m0)
+  ret void
+}