[SE][LV] Add test: early-exit loop with umin trip count should vectorize (NFC) (#196942)
See https://github.com/llvm/llvm-project/issues/196935
diff --git a/llvm/test/Transforms/LoopVectorize/early-exit-umin-trip-count.ll b/llvm/test/Transforms/LoopVectorize/early-exit-umin-trip-count.ll
new file mode 100644
index 0000000..36936ec
--- /dev/null
+++ b/llvm/test/Transforms/LoopVectorize/early-exit-umin-trip-count.ll
@@ -0,0 +1,77 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 6
+; RUN: opt -S -passes=loop-vectorize %s | FileCheck %s
+
+; TODO: The loop should be vectorized. The vectorizer needs to prove
+; (A umin B) u<= A to establish memory safety from the dereferenceable
+; assumption.
+;
+; long n = umin(count, length);
+; for (long i = 0; i < n; i++)
+; if (ptr[i] == 0) return null;
+; ...
+define ptr @main(i32 %length, ptr %ptr, i64 %0) #0 {
+; CHECK-LABEL: define ptr @main(
+; CHECK-SAME: i32 [[LENGTH:%.*]], ptr [[PTR:%.*]], i64 [[TMP0:%.*]]) #[[ATTR0:[0-9]+]] {
+; CHECK-NEXT: [[ENTRY:.*:]]
+; CHECK-NEXT: [[NULL_CHECK0:%.*]] = icmp eq i64 [[TMP0]], 0
+; CHECK-NEXT: br i1 [[NULL_CHECK0]], label %[[DEOPT:.*]], label %[[PREHEADER:.*]]
+; CHECK: [[PREHEADER]]:
+; CHECK-NEXT: [[LENGTH_64:%.*]] = zext i32 [[LENGTH]] to i64
+; CHECK-NEXT: [[EXIT:%.*]] = call i64 @llvm.umin.i64(i64 [[TMP0]], i64 [[LENGTH_64]])
+; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[PTR]], i64 8), "dereferenceable"(ptr [[PTR]], i64 [[LENGTH_64]]) ]
+; CHECK-NEXT: [[NULL_CHECK:%.*]] = icmp eq i32 [[LENGTH]], 0
+; CHECK-NEXT: br i1 [[NULL_CHECK]], label %[[DEOPT]], label %[[SCALAR_PH:.*]]
+; CHECK: [[SCALAR_PH]]:
+; CHECK-NEXT: br label %[[LOOP:.*]]
+; CHECK: [[LOOP]]:
+; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[IV_NEXT:%.*]], %[[LATCH:.*]] ], [ 0, %[[SCALAR_PH]] ]
+; CHECK-NEXT: [[ELEMENT_GEP:%.*]] = getelementptr i8, ptr [[PTR]], i64 [[IV]]
+; CHECK-NEXT: [[ELEMENT:%.*]] = load i8, ptr [[ELEMENT_GEP]], align 1
+; CHECK-NEXT: [[FOUND_CHECK:%.*]] = icmp eq i8 [[ELEMENT]], 0
+; CHECK-NEXT: br i1 [[FOUND_CHECK]], label %[[FOUND:.*]], label %[[LATCH]]
+; CHECK: [[LATCH]]:
+; CHECK-NEXT: [[IV_NEXT]] = add i64 [[IV]], 1
+; CHECK-NEXT: [[RANGE_CHECK:%.*]] = icmp ult i64 [[IV_NEXT]], [[EXIT]]
+; CHECK-NEXT: br i1 [[RANGE_CHECK]], label %[[LOOP]], label %[[DEOPT_LOOPEXIT:.*]]
+; CHECK: [[FOUND]]:
+; CHECK-NEXT: ret ptr null
+; CHECK: [[DEOPT_LOOPEXIT]]:
+; CHECK-NEXT: br label %[[DEOPT]]
+; CHECK: [[DEOPT]]:
+; CHECK-NEXT: unreachable
+;
+entry:
+ %null_check0 = icmp eq i64 %0, 0
+ br i1 %null_check0, label %deopt, label %preheader
+
+preheader: ; preds = %entry
+ %length.64 = zext i32 %length to i64
+ %exit = call i64 @llvm.umin.i64(i64 %0, i64 %length.64)
+ call void @llvm.assume(i1 true) [ "align"(ptr %ptr, i64 8), "dereferenceable"(ptr %ptr, i64 %length.64) ]
+ %null_check = icmp eq i32 %length, 0
+ br i1 %null_check, label %deopt, label %loop
+
+loop: ; preds = %latch, %preheader
+ %iv = phi i64 [ %iv.next, %latch ], [ 0, %preheader ]
+ %element_gep = getelementptr i8, ptr %ptr, i64 %iv
+ %element = load i8, ptr %element_gep, align 1
+ %found_check = icmp eq i8 %element, 0
+ br i1 %found_check, label %found, label %latch
+
+latch: ; preds = %loop
+ %iv.next = add i64 %iv, 1
+ %range_check = icmp ult i64 %iv.next, %exit
+ br i1 %range_check, label %loop, label %deopt
+
+found: ; preds = %loop
+ ret ptr null
+
+deopt: ; preds = %latch, %preheader
+ unreachable
+}
+
+declare i64 @llvm.umin.i64(i64, i64)
+
+declare void @llvm.assume(i1 noundef)
+
+attributes #0 = { nofree nosync }
