[llvm] [LoopVectorize] Add test case for minloc reduction (PR #141556)

[Madhur Amilkanthwar via llvm-commits]

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@@ -0,0 +1,86 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -passes=loop-vectorize -force-vector-width=4 -S %s | FileCheck %s --check-prefix=CHECK-REV-MIN
+
+; This test case is extracted from rnflow (fortran) benchmark in polyhedron benchmark suite.
+; The function minlst primarily takes two indices (i.e. range), scans backwards in the range
+; and returns the firstIV of the minimum value.
+
+define fastcc i32 @minlst(i32 %first_index, i32 %last_index, ptr %array) {
+; CHECK-REV-MIN-LABEL: define fastcc i32 @minlst(
+; CHECK-REV-MIN-SAME: i32 [[FIRST_INDEX:%.*]], i32 [[LAST_INDEX:%.*]], ptr [[ARRAY:%.*]]) {
+; CHECK-REV-MIN-NEXT:  [[ENTRY:.*]]:
+; CHECK-REV-MIN-NEXT:    [[FIRST_INDEX_SEXT:%.*]] = sext i32 [[FIRST_INDEX]] to i64
+; CHECK-REV-MIN-NEXT:    [[LAST_INDEX_NEG:%.*]] = sub i32 0, [[LAST_INDEX]]
+; CHECK-REV-MIN-NEXT:    [[LAST_INDEX_NEG_SEXT:%.*]] = sext i32 [[LAST_INDEX_NEG]] to i64
+; CHECK-REV-MIN-NEXT:    [[ADD:%.*]] = add nsw i64 [[FIRST_INDEX_SEXT]], [[LAST_INDEX_NEG_SEXT]]
+; CHECK-REV-MIN-NEXT:    [[SUB:%.*]] = sub nsw i64 0, [[ADD]]
+; CHECK-REV-MIN-NEXT:    [[INVARIANT_GEP:%.*]] = getelementptr i8, ptr [[ARRAY]], i64 -8
+; CHECK-REV-MIN-NEXT:    [[INVARIANT_GEP5:%.*]] = getelementptr i8, ptr [[ARRAY]], i64 -4
+; CHECK-REV-MIN-NEXT:    [[EARLY_EXIT_COND:%.*]] = icmp slt i64 [[ADD]], 0
+; CHECK-REV-MIN-NEXT:    br i1 [[EARLY_EXIT_COND]], label %[[LOOP_PREHEADER:.*]], [[DOT_CRIT_EDGE:label %.*]]
+; CHECK-REV-MIN:       [[LOOP_PREHEADER]]:
+; CHECK-REV-MIN-NEXT:    [[LAST_INDEX_SEXT:%.*]] = sext i32 [[LAST_INDEX]] to i64
+; CHECK-REV-MIN-NEXT:    br label %[[LOOP:.*]]
+; CHECK-REV-MIN:       [[LOOP]]:
+; CHECK-REV-MIN-NEXT:    [[IV:%.*]] = phi i64 [ [[LAST_INDEX_SEXT]], %[[LOOP_PREHEADER]] ], [ [[IV_NEXT:%.*]], %[[LOOP]] ]
+; CHECK-REV-MIN-NEXT:    [[TMP0:%.*]] = phi i64 [ [[TMP1:%.*]], %[[LOOP]] ], [ [[SUB]], %[[LOOP_PREHEADER]] ]
+; CHECK-REV-MIN-NEXT:    [[INDEX:%.*]] = phi i32 [ [[SELECT:%.*]], %[[LOOP]] ], [ [[LAST_INDEX]], %[[LOOP_PREHEADER]] ]
+; CHECK-REV-MIN-NEXT:    [[IV_NEXT]] = add nsw i64 [[IV]], -1
+; CHECK-REV-MIN-NEXT:    [[GEP:%.*]] = getelementptr float, ptr [[INVARIANT_GEP]], i64 [[IV]]
+; CHECK-REV-MIN-NEXT:    [[LOAD1:%.*]] = load float, ptr [[GEP]], align 4
+; CHECK-REV-MIN-NEXT:    [[INDEX_SEXT:%.*]] = sext i32 [[INDEX]] to i64
+; CHECK-REV-MIN-NEXT:    [[GEP6:%.*]] = getelementptr float, ptr [[INVARIANT_GEP5]], i64 [[INDEX_SEXT]]
+; CHECK-REV-MIN-NEXT:    [[LOAD2:%.*]] = load float, ptr [[GEP6]], align 4
+; CHECK-REV-MIN-NEXT:    [[CMP:%.*]] = fcmp contract olt float [[LOAD1]], [[LOAD2]]
+; CHECK-REV-MIN-NEXT:    [[IV_NEXT_TRUNC:%.*]] = trunc nsw i64 [[IV_NEXT]] to i32
+; CHECK-REV-MIN-NEXT:    [[SELECT]] = select i1 [[CMP]], i32 [[IV_NEXT_TRUNC]], i32 [[INDEX]]
+; CHECK-REV-MIN-NEXT:    [[TMP1]] = add nsw i64 [[TMP0]], -1
+; CHECK-REV-MIN-NEXT:    [[LOOP_COND:%.*]] = icmp sgt i64 [[TMP0]], 1
+; CHECK-REV-MIN-NEXT:    br i1 [[LOOP_COND]], label %[[LOOP]], label %[[DOT_CRIT_EDGE_LOOPEXIT:.*]]
+; CHECK-REV-MIN:       [[__CRIT_EDGE_LOOPEXIT:.*:]]
+; CHECK-REV-MIN-NEXT:    [[SELECT_LCSSA:%.*]] = phi i32 [ [[SELECT]], %[[LOOP]] ]
+; CHECK-REV-MIN-NEXT:    br [[DOT_CRIT_EDGE]]
+; CHECK-REV-MIN:       [[__CRIT_EDGE:.*:]]
+; CHECK-REV-MIN-NEXT:    [[LAST_INDEX_RET:%.*]] = phi i32 [ [[LAST_INDEX]], %[[ENTRY]] ], [ [[SELECT_LCSSA]], %[[DOT_CRIT_EDGE_LOOPEXIT]] ]
+; CHECK-REV-MIN-NEXT:    ret i32 [[LAST_INDEX_RET]]
+;
+entry:
+  %first_index_sext = sext i32 %first_index to i64
+  %last_index_neg = sub i32 0, %last_index
+  %last_index_neg_sext = sext i32 %last_index_neg to i64
+  %add = add nsw i64 %first_index_sext, %last_index_neg_sext
+  %diff = sub nsw i64 0, %add
+  %first_ptr = getelementptr i8, ptr %array, i64 -8
+  %second_ptr = getelementptr i8, ptr %array, i64 -4
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madhur13490 wrote:

No, I'd like to preserve the structure. 

https://github.com/llvm/llvm-project/pull/141556