[AMDGPU][Global-ISel] reuse extension related patterns in td file

However the imported rules can not be used for now because Global ISel
selectImpl() seems has some bug/limitation to create a illegl COPY
from VGPR to SGPR. So currently workaround this by not auto selecting these
patterns.

Fixes #61468

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D147780

llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp

@@ -3417,7 +3417,11 @@ bool AMDGPUInstructionSelector::select(MachineInstr &I) {
   case TargetOpcode::G_ZEXT:
   case TargetOpcode::G_ANYEXT:
   case TargetOpcode::G_SEXT_INREG:
-    if (selectImpl(I, *CoverageInfo))
+    // This is a workaround. For extension from type i1, `selectImpl()` uses
+    // patterns from TD file and generates an illegal VGPR to SGPR COPY as type
+    // i1 can only be hold in a SGPR class.
+    if (MRI->getType(I.getOperand(1).getReg()) != LLT::scalar(1) &&
+        selectImpl(I, *CoverageInfo))
       return true;
     return selectG_SZA_EXT(I);
   case TargetOpcode::G_BRCOND:

llvm/lib/Target/AMDGPU/SIInstructions.td

@@ -2020,13 +2020,13 @@ def : GCNPat <
 def : GCNPat <
   (i32 (sext i1:$src0)),
   (V_CNDMASK_B32_e64 /*src0mod*/(i32 0), /*src0*/(i32 0),
-                     /*src1mod*/(i32 0), /*src1*/(i32 -1), $src0)
+                     /*src1mod*/(i32 0), /*src1*/(i32 -1), i1:$src0)
 >;
 
 class Ext32Pat <SDNode ext> : GCNPat <
   (i32 (ext i1:$src0)),
   (V_CNDMASK_B32_e64 /*src0mod*/(i32 0), /*src0*/(i32 0),
-                     /*src1mod*/(i32 0), /*src1*/(i32 1), $src0)
+                     /*src1mod*/(i32 0), /*src1*/(i32 1), i1:$src0)
 >;
 
 def : Ext32Pat <zext>;