[AMDGPU] Add llvm.amdgcn.softwqm intrinsic

Add llvm.amdgcn.softwqm intrinsic which behaves like llvm.amdgcn.wqm
only if there is other WQM computation in the shader.

Reviewers: nhaehnle, tpr

Reviewed By: nhaehnle

Subscribers: arsenm, kzhuravl, jvesely, wdng, yaxunl, dstuttard, t-tye, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D64935

llvm-svn: 367097
diff --git a/llvm/lib/Target/AMDGPU/SIFixSGPRCopies.cpp b/llvm/lib/Target/AMDGPU/SIFixSGPRCopies.cpp
index 6249539..861fe74 100644
--- a/llvm/lib/Target/AMDGPU/SIFixSGPRCopies.cpp
+++ b/llvm/lib/Target/AMDGPU/SIFixSGPRCopies.cpp
@@ -617,6 +617,7 @@
         continue;
       case AMDGPU::COPY:
       case AMDGPU::WQM:
+      case AMDGPU::SOFT_WQM:
       case AMDGPU::WWM: {
         // If the destination register is a physical register there isn't really
         // much we can do to fix this.