[llvm] [VectorCombine] Enable transform 'scalarizeLoadExtract' for non constant indexes (PR #65445)

[Ben Shi via llvm-commits]

================
@@ -260,12 +368,28 @@ entry:
   ret i32 %r
 }
 
+define i32 @vscale_load_extract_idx_var_i64_not_known_valid_by_and(ptr %x, i64 %idx) {
+; CHECK-LABEL: @vscale_load_extract_idx_var_i64_not_known_valid_by_and(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[IDX_CLAMPED:%.*]] = and i64 [[IDX:%.*]], 4
+; CHECK-NEXT:    [[LV:%.*]] = load <vscale x 4 x i32>, ptr [[X:%.*]], align 16
+; CHECK-NEXT:    [[R:%.*]] = extractelement <vscale x 4 x i32> [[LV]], i64 [[IDX_CLAMPED]]
+; CHECK-NEXT:    ret i32 [[R]]
+;
+entry:
+  %idx.clamped = and i64 %idx, 4
+  %lv = load <vscale x 4 x i32>, ptr %x
+  %r = extractelement <vscale x 4 x i32> %lv, i64 %idx.clamped
+  ret i32 %r
+}
+
 define i32 @load_extract_idx_var_i64_known_valid_by_urem(ptr %x, i64 %idx) {
 ; CHECK-LABEL: @load_extract_idx_var_i64_known_valid_by_urem(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[IDX_CLAMPED:%.*]] = urem i64 [[IDX:%.*]], 4
-; CHECK-NEXT:    [[LV:%.*]] = load <4 x i32>, ptr [[X:%.*]], align 16
-; CHECK-NEXT:    [[R:%.*]] = extractelement <4 x i32> [[LV]], i64 [[IDX_CLAMPED]]
+; CHECK-NEXT:    [[IDX_FROZEN:%.*]] = freeze i64 [[IDX:%.*]]
----------------
benshi001 wrote:

This transform is safe and enabled by my change.

https://github.com/llvm/llvm-project/pull/65445