[AMDGPU] Fix illegal shrink of V_SUBB_U32 and V_ADDC_U32

If there is an immediate operand we shall not shrink V_SUBB_U32
and V_ADDC_U32, it does not fit e32 encoding.

Differential Revison: https://reviews.llvm.org/D34291

llvm-svn: 305840
diff --git a/llvm/lib/Target/AMDGPU/SIShrinkInstructions.cpp b/llvm/lib/Target/AMDGPU/SIShrinkInstructions.cpp
index c5f1217..96a1854 100644
--- a/llvm/lib/Target/AMDGPU/SIShrinkInstructions.cpp
+++ b/llvm/lib/Target/AMDGPU/SIShrinkInstructions.cpp
@@ -92,6 +92,8 @@
 
       case AMDGPU::V_ADDC_U32_e64:
       case AMDGPU::V_SUBB_U32_e64:
+        if (TII->getNamedOperand(MI, AMDGPU::OpName::src1)->isImm())
+          return false;
         // Additional verification is needed for sdst/src2.
         return true;