[Mem2Reg] Add test for uninitialized nonnull loads (NFC)

This shows a difference in behavior between the single block and
the multi block case.

Author: nikic

llvm/test/Transforms/Mem2Reg/preserve-nonnull-load-metadata.ll

@@ -1,15 +1,18 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt < %s -passes=mem2reg -S | FileCheck %s
 
 ; This tests that mem2reg preserves the !nonnull metadata on loads
 ; from allocas that get optimized out.
 
 ; Check the case where the alloca in question has a single store.
 define float* @single_store(float** %arg) {
-; CHECK-LABEL: define float* @single_store
-; CHECK: %arg.load = load float*, float** %arg, align 8
-; CHECK: [[ASSUME:%(.*)]] = icmp ne float* %arg.load, null
-; CHECK: call void @llvm.assume(i1 {{.*}}[[ASSUME]])
-; CHECK: ret float* %arg.load
+; CHECK-LABEL: @single_store(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[ARG_LOAD:%.*]] = load float*, float** [[ARG:%.*]], align 8
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp ne float* [[ARG_LOAD]], null
+; CHECK-NEXT:    call void @llvm.assume(i1 [[TMP0]])
+; CHECK-NEXT:    ret float* [[ARG_LOAD]]
+;
 entry:
   %buf = alloca float*
   %arg.load = load float*, float** %arg, align 8
@@ -21,11 +24,13 @@ entry:
 ; Check the case where the alloca in question has more than one
 ; store but still within one basic block.
 define float* @single_block(float** %arg) {
-; CHECK-LABEL: define float* @single_block
-; CHECK: %arg.load = load float*, float** %arg, align 8
-; CHECK: [[ASSUME:%(.*)]] = icmp ne float* %arg.load, null
-; CHECK: call void @llvm.assume(i1 {{.*}}[[ASSUME]])
-; CHECK: ret float* %arg.load
+; CHECK-LABEL: @single_block(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[ARG_LOAD:%.*]] = load float*, float** [[ARG:%.*]], align 8
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp ne float* [[ARG_LOAD]], null
+; CHECK-NEXT:    call void @llvm.assume(i1 [[TMP0]])
+; CHECK-NEXT:    ret float* [[ARG_LOAD]]
+;
 entry:
   %buf = alloca float*
   %arg.load = load float*, float** %arg, align 8
@@ -38,14 +43,15 @@ entry:
 ; Check the case where the alloca in question has more than one
 ; store and also reads ands writes in multiple blocks.
 define float* @multi_block(float** %arg) {
-; CHECK-LABEL: define float* @multi_block
-; CHECK-LABEL: entry:
-; CHECK: %arg.load = load float*, float** %arg, align 8
-; CHECK: br label %next
-; CHECK-LABEL: next:
-; CHECK: [[ASSUME:%(.*)]] = icmp ne float* %arg.load, null
-; CHECK: call void @llvm.assume(i1 {{.*}}[[ASSUME]])
-; CHECK: ret float* %arg.load
+; CHECK-LABEL: @multi_block(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[ARG_LOAD:%.*]] = load float*, float** [[ARG:%.*]], align 8
+; CHECK-NEXT:    br label [[NEXT:%.*]]
+; CHECK:       next:
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp ne float* [[ARG_LOAD]], null
+; CHECK-NEXT:    call void @llvm.assume(i1 [[TMP0]])
+; CHECK-NEXT:    ret float* [[ARG_LOAD]]
+;
 entry:
   %buf = alloca float*
   %arg.load = load float*, float** %arg, align 8
@@ -60,16 +66,16 @@ next:
 ; Check that we don't add an assume if it's not
 ; necessary i.e. the value is already implied to be nonnull
 define float* @no_assume(float** %arg) {
-; CHECK-LABEL: define float* @no_assume
-; CHECK-LABEL: entry:
-; CHECK: %arg.load = load float*, float** %arg, align 8
-; CHECK: %cn = icmp ne float* %arg.load, null
-; CHECK: br i1 %cn, label %next, label %fin
-; CHECK-LABEL: next:
-; CHECK-NOT: call void @llvm.assume
-; CHECK: ret float* %arg.load
-; CHECK-LABEL: fin:
-; CHECK: ret float* null
+; CHECK-LABEL: @no_assume(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[ARG_LOAD:%.*]] = load float*, float** [[ARG:%.*]], align 8
+; CHECK-NEXT:    [[CN:%.*]] = icmp ne float* [[ARG_LOAD]], null
+; CHECK-NEXT:    br i1 [[CN]], label [[NEXT:%.*]], label [[FIN:%.*]]
+; CHECK:       next:
+; CHECK-NEXT:    ret float* [[ARG_LOAD]]
+; CHECK:       fin:
+; CHECK-NEXT:    ret float* null
+;
 entry:
   %buf = alloca float*
   %arg.load = load float*, float** %arg, align 8
@@ -86,4 +92,41 @@ fin:
   ret float* null
 }
 
+define float* @no_store_single_load() {
+; CHECK-LABEL: @no_store_single_load(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    ret float* undef
+;
+entry:
+  %buf = alloca float*
+  %buf.load = load float*, float **%buf, !nonnull !0
+  ret float* %buf.load
+}
+
+define float* @no_store_multiple_loads(i1 %c) {
+; CHECK-LABEL: @no_store_multiple_loads(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br i1 [[C:%.*]], label [[IF:%.*]], label [[ELSE:%.*]]
+; CHECK:       if:
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp ne float* undef, null
+; CHECK-NEXT:    call void @llvm.assume(i1 [[TMP0]])
+; CHECK-NEXT:    ret float* undef
+; CHECK:       else:
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ne float* undef, null
+; CHECK-NEXT:    call void @llvm.assume(i1 [[TMP1]])
+; CHECK-NEXT:    ret float* undef
+;
+entry:
+  %buf = alloca float*
+  br i1 %c, label %if, label %else
+
+if:
+  %buf.load = load float*, float **%buf, !nonnull !0
+  ret float* %buf.load
+
+  else:
+  %buf.load2 = load float*, float **%buf, !nonnull !0
+  ret float* %buf.load2
+}
+
 !0 = !{}