[RISCV][SelectionDAGBuilder] Fix an implicit scalable TypeSize to fixed size conversion in getUniformBase.

[craig.topper]

Summary

If the index needs to be scaled by a scalable size, just give up.

Fixes PR63459

[frasercrmck]

LGTM

[RKSimon]

LGTM

llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

static bool getUniformBase(const Value *Ptr, SDValue &Base, SDValue &Index,
 
   const Value *BasePtr = GEP->getPointerOperand();
   const Value *IndexVal = GEP->getOperand(GEP->getNumOperands() - 1);
 
   // Make sure the base is scalar and the index is a vector.
   if (BasePtr->getType()->isVectorTy() || !IndexVal->getType()->isVectorTy())
     return false;
 
-  uint64_t ScaleVal = DL.getTypeAllocSize(GEP->getResultElementType());
+  TypeSize ScaleVal = DL.getTypeAllocSize(GEP->getResultElementType());
+  if (ScaleVal.isScalable())
+    return false;
 
   // Target may not support the required addressing mode.
   if (ScaleVal != 1 &&
-      !TLI.isLegalScaleForGatherScatter(ScaleVal, ElemSize))
+      !TLI.isLegalScaleForGatherScatter(ScaleVal.getFixedValue(), ElemSize))
     return false;
 
   Base = SDB->getValue(BasePtr);
   Index = SDB->getValue(IndexVal);
   IndexType = ISD::SIGNED_SCALED;
 
   Scale =
       DAG.getTargetConstant(ScaleVal, SDB->getCurSDLoc(), TLI.getPointerTy(DL));

llvm/test/CodeGen/RISCV/rvv/pr63459.ll

+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 2
+; RUN: llc < %s -mtriple=riscv64 -mattr=+v | FileCheck %s
+
+define void @snork(ptr %arg, <vscale x 2 x i64> %arg1) {
+; CHECK-LABEL: snork:
+; CHECK:       # %bb.0: # %bb
+; CHECK-NEXT:    csrr a1, vlenb
+; CHECK-NEXT:    vsetvli a2, zero, e64, m2, ta, ma
+; CHECK-NEXT:    vmul.vx v8, v8, a1
+; CHECK-NEXT:    vsetvli zero, zero, e32, m1, ta, ma
+; CHECK-NEXT:    vmv.v.i v10, 1
+; CHECK-NEXT:    vsetivli zero, 4, e32, m1, ta, ma
+; CHECK-NEXT:    vsoxei64.v v10, (a0), v8
+; CHECK-NEXT:    ret
+bb:
+  %getelementptr = getelementptr inbounds <vscale x 2 x i32>, ptr %arg, <vscale x 2 x i64> %arg1
+  tail call void @llvm.vp.scatter.nxv2i32.nxv2p0(<vscale x 2 x i32> shufflevector (<vscale x 2 x i32> insertelement (<vscale x 2 x i32> poison, i32 1, i32 0), <vscale x 2 x i32> poison, <vscale x 2 x i32> zeroinitializer), <vscale x 2 x ptr> align 4 %getelementptr, <vscale x 2 x i1> shufflevector (<vscale x 2 x i1> insertelement (<vscale x 2 x i1> poison, i1 true, i64 0), <vscale x 2 x i1> poison, <vscale x 2 x i32> zeroinitializer), i32 4)
+  ret void
+}
+
+declare void @llvm.vp.scatter.nxv2i32.nxv2p0(<vscale x 2 x i32>, <vscale x 2 x ptr>, <vscale x 2 x i1>, i32)