[Loads] Fix crash in isSafeToLoadUnconditionally with scalable accessed type (#82650)

This fixes #82606 by updating isSafeToLoadUnconditionally to handle
fixed sized loads from a scalable accessed type.

Author: lukel97

llvm/lib/Analysis/Loads.cpp

@@ -364,7 +364,7 @@ bool llvm::isSafeToLoadUnconditionally(Value *V, Align Alignment, APInt &Size,
 
   if (Size.getBitWidth() > 64)
     return false;
-  const uint64_t LoadSize = Size.getZExtValue();
+  const TypeSize LoadSize = TypeSize::getFixed(Size.getZExtValue());
 
   // Otherwise, be a little bit aggressive by scanning the local block where we
   // want to check to see if the pointer is already being loaded or stored
@@ -414,11 +414,11 @@ bool llvm::isSafeToLoadUnconditionally(Value *V, Align Alignment, APInt &Size,
 
     // Handle trivial cases.
     if (AccessedPtr == V &&
-        LoadSize <= DL.getTypeStoreSize(AccessedTy))
+        TypeSize::isKnownLE(LoadSize, DL.getTypeStoreSize(AccessedTy)))
       return true;
 
     if (AreEquivalentAddressValues(AccessedPtr->stripPointerCasts(), V) &&
-        LoadSize <= DL.getTypeStoreSize(AccessedTy))
+        TypeSize::isKnownLE(LoadSize, DL.getTypeStoreSize(AccessedTy)))
       return true;
   }
   return false;

llvm/test/Transforms/VectorCombine/RISCV/load-widening.ll

@@ -0,0 +1,19 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
+; RUN: opt < %s -passes=vector-combine -S -mtriple=riscv32 -mattr=+v | FileCheck %s
+; RUN: opt < %s -passes=vector-combine -S -mtriple=riscv64 -mattr=+v | FileCheck %s
+
+define void @fixed_load_scalable_src(ptr %p) {
+; CHECK-LABEL: define void @fixed_load_scalable_src(
+; CHECK-SAME: ptr [[P:%.*]]) #[[ATTR0:[0-9]+]] {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    store <vscale x 4 x i16> zeroinitializer, ptr [[P]], align 8
+; CHECK-NEXT:    [[TMP0:%.*]] = load <4 x i16>, ptr [[P]], align 8
+; CHECK-NEXT:    [[TMP1:%.*]] = shufflevector <4 x i16> [[TMP0]], <4 x i16> zeroinitializer, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 poison, i32 poison, i32 poison, i32 poison>
+; CHECK-NEXT:    ret void
+;
+entry:
+  store <vscale x 4 x i16> zeroinitializer, ptr %p
+  %0 = load <4 x i16>, ptr %p
+  %1 = shufflevector <4 x i16> %0, <4 x i16> zeroinitializer, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 poison, i32 poison, i32 poison, i32 poison>
+  ret void
+}