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

Madhur Amilkanthwar via llvm-commits llvm-commits at lists.llvm.org
Tue May 27 05:31:02 PDT 2025


https://github.com/madhur13490 updated https://github.com/llvm/llvm-project/pull/141556

>From 81c03736bb7948d74d4a044dae669db9f3b3c5c7 Mon Sep 17 00:00:00 2001
From: Madhur Amilkanthwar <madhura at nvidia.com>
Date: Mon, 26 May 2025 07:14:54 -0700
Subject: [PATCH 1/2] [LoopVectorize] Add test case for minloc reduction

This patch adds a test case extracted from Polyhedron benchmark.
https://fortran.uk/fortran-compiler-comparisons/the-polyhedron-solutions-benchmark-suite/

The test is specifically interesting for vectorizing min/max reduction
pattern.
---
 .../LoopVectorize/last-min-index.ll           | 84 +++++++++++++++++++
 1 file changed, 84 insertions(+)
 create mode 100644 llvm/test/Transforms/LoopVectorize/last-min-index.ll

diff --git a/llvm/test/Transforms/LoopVectorize/last-min-index.ll b/llvm/test/Transforms/LoopVectorize/last-min-index.ll
new file mode 100644
index 0000000000000..f69145eafa74a
--- /dev/null
+++ b/llvm/test/Transforms/LoopVectorize/last-min-index.ll
@@ -0,0 +1,84 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -passes=loop-vectorize -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 %.0.val, i32 %.0.val1, ptr %.0.val3) {
+; CHECK-REV-MIN-LABEL: define internal fastcc i32 @_QFcptrf2Pminlst(
+; CHECK-REV-MIN-SAME: i32 [[DOT0_VAL:%.*]], i32 [[DOT0_VAL1:%.*]], ptr [[DOT0_VAL3:%.*]]) unnamed_addr {
+; CHECK-REV-MIN-NEXT:    [[TMP1:%.*]] = sext i32 [[DOT0_VAL]] to i64
+; CHECK-REV-MIN-NEXT:    [[TMP2:%.*]] = sub i32 0, [[DOT0_VAL1]]
+; CHECK-REV-MIN-NEXT:    [[TMP3:%.*]] = sext i32 [[TMP2]] to i64
+; CHECK-REV-MIN-NEXT:    [[TMP4:%.*]] = add nsw i64 [[TMP1]], [[TMP3]]
+; CHECK-REV-MIN-NEXT:    [[TMP5:%.*]] = sub nsw i64 0, [[TMP4]]
+; CHECK-REV-MIN-NEXT:    [[INVARIANT_GEP:%.*]] = getelementptr i8, ptr [[DOT0_VAL3]], i64 -8
+; CHECK-REV-MIN-NEXT:    [[INVARIANT_GEP5:%.*]] = getelementptr i8, ptr [[DOT0_VAL3]], i64 -4
+; CHECK-REV-MIN-NEXT:    [[TMP6:%.*]] = icmp slt i64 [[TMP4]], 0
+; CHECK-REV-MIN-NEXT:    br i1 [[TMP6]], label %[[DOTLR_PH_PREHEADER:.*]], [[DOT_CRIT_EDGE:label %.*]]
+; CHECK-REV-MIN:       [[_LR_PH_PREHEADER:.*:]]
+; CHECK-REV-MIN-NEXT:    [[TMP7:%.*]] = sext i32 [[DOT0_VAL1]] to i64
+; CHECK-REV-MIN-NEXT:    br label %[[DOTLR_PH:.*]]
+; CHECK-REV-MIN:       [[_LR_PH:.*:]]
+; CHECK-REV-MIN-NEXT:    [[INDVARS_IV:%.*]] = phi i64 [ [[TMP7]], %[[DOTLR_PH_PREHEADER]] ], [ [[INDVARS_IV_NEXT:%.*]], %[[DOTLR_PH]] ]
+; CHECK-REV-MIN-NEXT:    [[TMP8:%.*]] = phi i64 [ [[TMP14:%.*]], %[[DOTLR_PH]] ], [ [[TMP5]], %[[DOTLR_PH_PREHEADER]] ]
+; CHECK-REV-MIN-NEXT:    [[DOT07:%.*]] = phi i32 [ [[DOT1:%.*]], %[[DOTLR_PH]] ], [ [[DOT0_VAL1]], %[[DOTLR_PH_PREHEADER]] ]
+; CHECK-REV-MIN-NEXT:    [[INDVARS_IV_NEXT]] = add nsw i64 [[INDVARS_IV]], -1
+; CHECK-REV-MIN-NEXT:    [[GEP:%.*]] = getelementptr float, ptr [[INVARIANT_GEP]], i64 [[INDVARS_IV]]
+; CHECK-REV-MIN-NEXT:    [[TMP9:%.*]] = load float, ptr [[GEP]], align 4
+; CHECK-REV-MIN-NEXT:    [[TMP10:%.*]] = sext i32 [[DOT07]] to i64
+; CHECK-REV-MIN-NEXT:    [[GEP6:%.*]] = getelementptr float, ptr [[INVARIANT_GEP5]], i64 [[TMP10]]
+; CHECK-REV-MIN-NEXT:    [[TMP11:%.*]] = load float, ptr [[GEP6]], align 4
+; CHECK-REV-MIN-NEXT:    [[TMP12:%.*]] = fcmp contract olt float [[TMP9]], [[TMP11]]
+; CHECK-REV-MIN-NEXT:    [[TMP13:%.*]] = trunc nsw i64 [[INDVARS_IV_NEXT]] to i32
+; CHECK-REV-MIN-NEXT:    [[DOT1]] = select i1 [[TMP12]], i32 [[TMP13]], i32 [[DOT07]]
+; CHECK-REV-MIN-NEXT:    [[TMP14]] = add nsw i64 [[TMP8]], -1
+; CHECK-REV-MIN-NEXT:    [[TMP15:%.*]] = icmp sgt i64 [[TMP8]], 1
+; CHECK-REV-MIN-NEXT:    br i1 [[TMP15]], label %[[DOTLR_PH]], label %[[DOT_CRIT_EDGE_LOOPEXIT:.*]]
+; CHECK-REV-MIN:       [[__CRIT_EDGE_LOOPEXIT:.*:]]
+; CHECK-REV-MIN-NEXT:    [[DOT1_LCSSA:%.*]] = phi i32 [ [[DOT1]], %[[DOTLR_PH]] ]
+; CHECK-REV-MIN-NEXT:    br [[DOT_CRIT_EDGE]]
+; CHECK-REV-MIN:       [[__CRIT_EDGE:.*:]]
+; CHECK-REV-MIN-NEXT:    [[DOT0_LCSSA:%.*]] = phi i32 [ [[DOT0_VAL1]], [[TMP0:%.*]] ], [ [[DOT1_LCSSA]], %[[DOT_CRIT_EDGE_LOOPEXIT]] ]
+; CHECK-REV-MIN-NEXT:    ret i32 [[DOT0_LCSSA]]
+;
+  %1 = sext i32 %.0.val to i64
+  %2 = sub i32 0, %.0.val1
+  %3 = sext i32 %2 to i64
+  %4 = add nsw i64 %1, %3
+  %5 = sub nsw i64 0, %4
+  %invariant.gep = getelementptr i8, ptr %.0.val3, i64 -8
+  %invariant.gep5 = getelementptr i8, ptr %.0.val3, i64 -4
+  %6 = icmp slt i64 %4, 0
+  br i1 %6, label %.lr.ph.preheader, label %._crit_edge
+
+.lr.ph.preheader:                                 ; preds = %0
+  %7 = sext i32 %.0.val1 to i64
+  br label %.lr.ph
+
+.lr.ph:                                           ; preds = %.lr.ph.preheader, %.lr.ph
+  %indvars.iv = phi i64 [ %7, %.lr.ph.preheader ], [ %indvars.iv.next, %.lr.ph ]
+  %8 = phi i64 [ %14, %.lr.ph ], [ %5, %.lr.ph.preheader ]
+  %.07 = phi i32 [ %.1, %.lr.ph ], [ %.0.val1, %.lr.ph.preheader ]
+  %indvars.iv.next = add nsw i64 %indvars.iv, -1
+  %gep = getelementptr float, ptr %invariant.gep, i64 %indvars.iv
+  %9 = load float, ptr %gep, align 4
+  %10 = sext i32 %.07 to i64
+  %gep6 = getelementptr float, ptr %invariant.gep5, i64 %10
+  %11 = load float, ptr %gep6, align 4
+  %12 = fcmp contract olt float %9, %11
+  %13 = trunc nsw i64 %indvars.iv.next to i32
+  %.1 = select i1 %12, i32 %13, i32 %.07
+  %14 = add nsw i64 %8, -1
+  %15 = icmp sgt i64 %8, 1
+  br i1 %15, label %.lr.ph, label %._crit_edge.loopexit
+
+._crit_edge.loopexit:                             ; preds = %.lr.ph
+  %.1.lcssa = phi i32 [ %.1, %.lr.ph ]
+  br label %._crit_edge
+
+._crit_edge:                                      ; preds = %._crit_edge.loopexit, %0
+  %.0.lcssa = phi i32 [ %.0.val1, %0 ], [ %.1.lcssa, %._crit_edge.loopexit ]
+  ret i32 %.0.lcssa
+}

>From 936d6ca3401a94ded2a7cd7672477b291aaada84 Mon Sep 17 00:00:00 2001
From: Madhur Amilkanthwar <madhura at nvidia.com>
Date: Tue, 27 May 2025 05:29:07 -0700
Subject: [PATCH 2/2] Address review comments

---
 .../LoopVectorize/last-min-index.ll           | 136 +++++++++---------
 1 file changed, 69 insertions(+), 67 deletions(-)

diff --git a/llvm/test/Transforms/LoopVectorize/last-min-index.ll b/llvm/test/Transforms/LoopVectorize/last-min-index.ll
index f69145eafa74a..c99766cfcd318 100644
--- a/llvm/test/Transforms/LoopVectorize/last-min-index.ll
+++ b/llvm/test/Transforms/LoopVectorize/last-min-index.ll
@@ -1,84 +1,86 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
-; RUN: opt -passes=loop-vectorize -S %s | FileCheck %s --check-prefix=CHECK-REV-MIN
+; 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 %.0.val, i32 %.0.val1, ptr %.0.val3) {
-; CHECK-REV-MIN-LABEL: define internal fastcc i32 @_QFcptrf2Pminlst(
-; CHECK-REV-MIN-SAME: i32 [[DOT0_VAL:%.*]], i32 [[DOT0_VAL1:%.*]], ptr [[DOT0_VAL3:%.*]]) unnamed_addr {
-; CHECK-REV-MIN-NEXT:    [[TMP1:%.*]] = sext i32 [[DOT0_VAL]] to i64
-; CHECK-REV-MIN-NEXT:    [[TMP2:%.*]] = sub i32 0, [[DOT0_VAL1]]
-; CHECK-REV-MIN-NEXT:    [[TMP3:%.*]] = sext i32 [[TMP2]] to i64
-; CHECK-REV-MIN-NEXT:    [[TMP4:%.*]] = add nsw i64 [[TMP1]], [[TMP3]]
-; CHECK-REV-MIN-NEXT:    [[TMP5:%.*]] = sub nsw i64 0, [[TMP4]]
-; CHECK-REV-MIN-NEXT:    [[INVARIANT_GEP:%.*]] = getelementptr i8, ptr [[DOT0_VAL3]], i64 -8
-; CHECK-REV-MIN-NEXT:    [[INVARIANT_GEP5:%.*]] = getelementptr i8, ptr [[DOT0_VAL3]], i64 -4
-; CHECK-REV-MIN-NEXT:    [[TMP6:%.*]] = icmp slt i64 [[TMP4]], 0
-; CHECK-REV-MIN-NEXT:    br i1 [[TMP6]], label %[[DOTLR_PH_PREHEADER:.*]], [[DOT_CRIT_EDGE:label %.*]]
-; CHECK-REV-MIN:       [[_LR_PH_PREHEADER:.*:]]
-; CHECK-REV-MIN-NEXT:    [[TMP7:%.*]] = sext i32 [[DOT0_VAL1]] to i64
-; CHECK-REV-MIN-NEXT:    br label %[[DOTLR_PH:.*]]
-; CHECK-REV-MIN:       [[_LR_PH:.*:]]
-; CHECK-REV-MIN-NEXT:    [[INDVARS_IV:%.*]] = phi i64 [ [[TMP7]], %[[DOTLR_PH_PREHEADER]] ], [ [[INDVARS_IV_NEXT:%.*]], %[[DOTLR_PH]] ]
-; CHECK-REV-MIN-NEXT:    [[TMP8:%.*]] = phi i64 [ [[TMP14:%.*]], %[[DOTLR_PH]] ], [ [[TMP5]], %[[DOTLR_PH_PREHEADER]] ]
-; CHECK-REV-MIN-NEXT:    [[DOT07:%.*]] = phi i32 [ [[DOT1:%.*]], %[[DOTLR_PH]] ], [ [[DOT0_VAL1]], %[[DOTLR_PH_PREHEADER]] ]
-; CHECK-REV-MIN-NEXT:    [[INDVARS_IV_NEXT]] = add nsw i64 [[INDVARS_IV]], -1
-; CHECK-REV-MIN-NEXT:    [[GEP:%.*]] = getelementptr float, ptr [[INVARIANT_GEP]], i64 [[INDVARS_IV]]
-; CHECK-REV-MIN-NEXT:    [[TMP9:%.*]] = load float, ptr [[GEP]], align 4
-; CHECK-REV-MIN-NEXT:    [[TMP10:%.*]] = sext i32 [[DOT07]] to i64
-; CHECK-REV-MIN-NEXT:    [[GEP6:%.*]] = getelementptr float, ptr [[INVARIANT_GEP5]], i64 [[TMP10]]
-; CHECK-REV-MIN-NEXT:    [[TMP11:%.*]] = load float, ptr [[GEP6]], align 4
-; CHECK-REV-MIN-NEXT:    [[TMP12:%.*]] = fcmp contract olt float [[TMP9]], [[TMP11]]
-; CHECK-REV-MIN-NEXT:    [[TMP13:%.*]] = trunc nsw i64 [[INDVARS_IV_NEXT]] to i32
-; CHECK-REV-MIN-NEXT:    [[DOT1]] = select i1 [[TMP12]], i32 [[TMP13]], i32 [[DOT07]]
-; CHECK-REV-MIN-NEXT:    [[TMP14]] = add nsw i64 [[TMP8]], -1
-; CHECK-REV-MIN-NEXT:    [[TMP15:%.*]] = icmp sgt i64 [[TMP8]], 1
-; CHECK-REV-MIN-NEXT:    br i1 [[TMP15]], label %[[DOTLR_PH]], label %[[DOT_CRIT_EDGE_LOOPEXIT:.*]]
+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:    [[DOT1_LCSSA:%.*]] = phi i32 [ [[DOT1]], %[[DOTLR_PH]] ]
+; 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:    [[DOT0_LCSSA:%.*]] = phi i32 [ [[DOT0_VAL1]], [[TMP0:%.*]] ], [ [[DOT1_LCSSA]], %[[DOT_CRIT_EDGE_LOOPEXIT]] ]
-; CHECK-REV-MIN-NEXT:    ret i32 [[DOT0_LCSSA]]
+; 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]]
 ;
-  %1 = sext i32 %.0.val to i64
-  %2 = sub i32 0, %.0.val1
-  %3 = sext i32 %2 to i64
-  %4 = add nsw i64 %1, %3
-  %5 = sub nsw i64 0, %4
-  %invariant.gep = getelementptr i8, ptr %.0.val3, i64 -8
-  %invariant.gep5 = getelementptr i8, ptr %.0.val3, i64 -4
-  %6 = icmp slt i64 %4, 0
-  br i1 %6, label %.lr.ph.preheader, label %._crit_edge
+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
+  %early_exit_cond = icmp slt i64 %add, 0
+  br i1 %early_exit_cond, label %loop.preheader, label %._crit_edge
 
-.lr.ph.preheader:                                 ; preds = %0
-  %7 = sext i32 %.0.val1 to i64
-  br label %.lr.ph
+loop.preheader:                                 ; preds = %entry
+  %last_index_sext = sext i32 %last_index to i64
+  br label %loop
 
-.lr.ph:                                           ; preds = %.lr.ph.preheader, %.lr.ph
-  %indvars.iv = phi i64 [ %7, %.lr.ph.preheader ], [ %indvars.iv.next, %.lr.ph ]
-  %8 = phi i64 [ %14, %.lr.ph ], [ %5, %.lr.ph.preheader ]
-  %.07 = phi i32 [ %.1, %.lr.ph ], [ %.0.val1, %.lr.ph.preheader ]
-  %indvars.iv.next = add nsw i64 %indvars.iv, -1
-  %gep = getelementptr float, ptr %invariant.gep, i64 %indvars.iv
-  %9 = load float, ptr %gep, align 4
-  %10 = sext i32 %.07 to i64
-  %gep6 = getelementptr float, ptr %invariant.gep5, i64 %10
-  %11 = load float, ptr %gep6, align 4
-  %12 = fcmp contract olt float %9, %11
-  %13 = trunc nsw i64 %indvars.iv.next to i32
-  %.1 = select i1 %12, i32 %13, i32 %.07
-  %14 = add nsw i64 %8, -1
-  %15 = icmp sgt i64 %8, 1
-  br i1 %15, label %.lr.ph, label %._crit_edge.loopexit
+loop:                                           ; preds = %loop.preheader, %loop
+  %iv = phi i64 [ %last_index_sext, %loop.preheader ], [ %iv.next, %loop ]
+  %dec_iv = phi i64 [ %dec, %loop ], [ %diff, %loop.preheader ]
+  %index = phi i32 [ %select, %loop ], [ %last_index, %loop.preheader ]
+  %iv.next = add nsw i64 %iv, -1
+  %load1_ptr = getelementptr float, ptr %first_ptr, i64 %iv
+  %load1 = load float, ptr %load1_ptr, align 4
+  %index_sext = sext i32 %index to i64
+  %load2_ptr = getelementptr float, ptr %second_ptr, i64 %index_sext
+  %load2 = load float, ptr %load2_ptr, align 4
+  %cmp = fcmp contract olt float %load1, %load2
+  %iv.next.trunc = trunc nsw i64 %iv.next to i32
+  %select = select i1 %cmp, i32 %iv.next.trunc, i32 %index
+  %dec = add nsw i64 %dec_iv, -1
+  %loop_cond = icmp sgt i64 %dec_iv, 1
+  br i1 %loop_cond, label %loop, label %._crit_edge.loopexit
 
-._crit_edge.loopexit:                             ; preds = %.lr.ph
-  %.1.lcssa = phi i32 [ %.1, %.lr.ph ]
+._crit_edge.loopexit:                             ; preds = %loop
+  %select.lcssa = phi i32 [ %select, %loop ]
   br label %._crit_edge
 
 ._crit_edge:                                      ; preds = %._crit_edge.loopexit, %0
-  %.0.lcssa = phi i32 [ %.0.val1, %0 ], [ %.1.lcssa, %._crit_edge.loopexit ]
-  ret i32 %.0.lcssa
+  %last_index_ret = phi i32 [ %last_index, %entry ], [ %select.lcssa, %._crit_edge.loopexit ]
+  ret i32 %last_index_ret
 }



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