[InstCombine] Add tests for folding align assumes into load metadata.

Author: fhahn

llvm/test/Transforms/InstCombine/assume-align.ll

@@ -1,4 +1,4 @@
-; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-globals smart
 ; RUN: opt -S -passes=instcombine,simplifycfg < %s 2>&1 | FileCheck %s
 
 declare void @llvm.assume(i1 noundef)
@@ -122,3 +122,52 @@ define i8 @assume_align_non_pow2(ptr %p) {
   %v = load i8, ptr %p
   ret i8 %v
 }
+
+; TODO: Can fold alignment assumption into !align metadata on load.
+define ptr @fold_assume_align_pow2_of_loaded_pointer_into_align_metadata(ptr %p) {
+; CHECK-LABEL: @fold_assume_align_pow2_of_loaded_pointer_into_align_metadata(
+; CHECK-NEXT:    [[P2:%.*]] = load ptr, ptr [[P:%.*]], align 8
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "align"(ptr [[P2]], i64 8) ]
+; CHECK-NEXT:    ret ptr [[P2]]
+;
+  %p2 = load ptr, ptr %p
+  call void @llvm.assume(i1 true) [ "align"(ptr %p2, i64 8) ]
+  ret ptr %p2
+}
+
+define ptr @dont_fold_assume_align_pow2_of_loaded_pointer_into_align_metadata_due_to_call(ptr %p) {
+; CHECK-LABEL: @dont_fold_assume_align_pow2_of_loaded_pointer_into_align_metadata_due_to_call(
+; CHECK-NEXT:    [[P2:%.*]] = load ptr, ptr [[P:%.*]], align 8
+; CHECK-NEXT:    call void @g(i64 0)
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "align"(ptr [[P2]], i64 8) ]
+; CHECK-NEXT:    ret ptr [[P2]]
+;
+  %p2 = load ptr, ptr %p
+  call void @g(i64 0)
+  call void @llvm.assume(i1 true) [ "align"(ptr %p2, i64 8) ]
+  ret ptr %p2
+}
+
+; !align must have a power-of-2 alignment.
+define ptr @dont_fold_assume_align_non_pow2_of_loaded_pointer_into_align_metadata(ptr %p) {
+; CHECK-LABEL: @dont_fold_assume_align_non_pow2_of_loaded_pointer_into_align_metadata(
+; CHECK-NEXT:    [[P2:%.*]] = load ptr, ptr [[P:%.*]], align 8
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "align"(ptr [[P2]], i64 13) ]
+; CHECK-NEXT:    ret ptr [[P2]]
+;
+  %p2 = load ptr, ptr %p
+  call void @llvm.assume(i1 true) [ "align"(ptr %p2, i64 13) ]
+  ret ptr %p2
+}
+
+; !align must have a power-of-2 alignment.
+define ptr @dont_fold_assume_align_zero_of_loaded_pointer_into_align_metadata(ptr %p) {
+; CHECK-LABEL: @dont_fold_assume_align_zero_of_loaded_pointer_into_align_metadata(
+; CHECK-NEXT:    [[P2:%.*]] = load ptr, ptr [[P:%.*]], align 8
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "align"(ptr [[P2]], i64 0) ]
+; CHECK-NEXT:    ret ptr [[P2]]
+;
+  %p2 = load ptr, ptr %p
+  call void @llvm.assume(i1 true) [ "align"(ptr %p2, i64 0) ]
+  ret ptr %p2
+}