Index: lib/Target/AMDGPU/SIInstrInfo.td
===================================================================
--- lib/Target/AMDGPU/SIInstrInfo.td
+++ lib/Target/AMDGPU/SIInstrInfo.td
@@ -1195,7 +1195,13 @@
 
   // Suppress src2 implied by type since the 32-bit encoding uses an
   // implicit VCC use.
-  let Ins32 = (ins Src0RC32:$src0, Src1RC32:$src1);
+  //
+  // We also use VCSrc_32 to exclude literal constants, even though
+  // the encoding normally allows them since the implicit VCC use
+  // means using one would always violate the constant bus
+  // restriction. SGPRs are still allowed because it should
+  // technically be possible to use VCC again as src0.
+  let Ins32 = (ins VCSrc_32:$src0, Src1RC32:$src1);
 }
 
 class VOP3b_Profile<ValueType vt> : VOPProfile<[vt, vt, vt, vt]> {