AMDGPU: Verify that SOP2/SOPC instructions have at most one immediate operand

Summary:
No test case because I don't know of a way to trigger this, but I
accidentally caused this to fail while working on a different change.

Change-Id: I8015aa447fe27163cc4e4902205a203bd44bf7e3

Reviewers: arsenm, rampitec

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

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D61490

llvm-svn: 360123
diff --git a/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp b/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
index 8f4a073..1e77d63 100644
--- a/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
@@ -3191,6 +3191,24 @@
     }
   }
 
+  if (isSOP2(MI) || isSOPC(MI)) {
+    const MachineOperand &Src0 = MI.getOperand(Src0Idx);
+    const MachineOperand &Src1 = MI.getOperand(Src1Idx);
+    unsigned Immediates = 0;
+
+    if (!Src0.isReg() &&
+        !isInlineConstant(Src0, Desc.OpInfo[Src0Idx].OperandType))
+      Immediates++;
+    if (!Src1.isReg() &&
+        !isInlineConstant(Src1, Desc.OpInfo[Src1Idx].OperandType))
+      Immediates++;
+
+    if (Immediates > 1) {
+      ErrInfo = "SOP2/SOPC instruction requires too many immediate constants";
+      return false;
+    }
+  }
+
   if (isSOPK(MI)) {
     auto Op = getNamedOperand(MI, AMDGPU::OpName::simm16);
     if (Desc.isBranch()) {