[llvm] [LoopUnroll] Introduce parallel accumulators when unrolling FP reductions. (PR #166630)
Julian Nagele via llvm-commits
llvm-commits at lists.llvm.org
Thu Nov 20 09:39:50 PST 2025
https://github.com/juliannagele updated https://github.com/llvm/llvm-project/pull/166630
>From 214c03f57100854b00f7667fe71d146475130ec4 Mon Sep 17 00:00:00 2001
From: Julian Nagele <j_nagele at apple.com>
Date: Wed, 5 Nov 2025 20:19:12 +0000
Subject: [PATCH 1/2] [LoopUnroll] Introduce parallel accumulators when
unrolling FP reductions.
---
llvm/lib/Transforms/Utils/LoopUnroll.cpp | 12 +-
.../LoopUnroll/partial-unroll-reductions.ll | 21 ++-
.../LoopUnroll/runtime-unroll-reductions.ll | 133 ++++++++++++++++++
3 files changed, 156 insertions(+), 10 deletions(-)
diff --git a/llvm/lib/Transforms/Utils/LoopUnroll.cpp b/llvm/lib/Transforms/Utils/LoopUnroll.cpp
index 94dfd3a974923..d3d7faf6ab7ff 100644
--- a/llvm/lib/Transforms/Utils/LoopUnroll.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUnroll.cpp
@@ -1094,6 +1094,7 @@ llvm::UnrollLoop(Loop *L, UnrollLoopOptions ULO, LoopInfo *LI,
if (!RdxResult) {
RdxResult = PartialReductions.front();
IRBuilder Builder(ExitBlock, ExitBlock->getFirstNonPHIIt());
+ Builder.setFastMathFlags(Reductions.begin()->second.getFastMathFlags());
RecurKind RK = Reductions.begin()->second.getRecurrenceKind();
for (Instruction *RdxPart : drop_begin(PartialReductions)) {
RdxResult = Builder.CreateBinOp(
@@ -1256,14 +1257,19 @@ llvm::canParallelizeReductionWhenUnrolling(PHINode &Phi, Loop *L,
return std::nullopt;
RecurKind RK = RdxDesc.getRecurrenceKind();
// Skip unsupported reductions.
- // TODO: Handle additional reductions, including FP and min-max
- // reductions.
- if (!RecurrenceDescriptor::isIntegerRecurrenceKind(RK) ||
+ // TODO: Handle additional reductions, including min-max reductions.
+ if (!(RecurrenceDescriptor::isIntegerRecurrenceKind(RK) ||
+ RecurrenceDescriptor::isFloatingPointRecurrenceKind(RK)) ||
RecurrenceDescriptor::isAnyOfRecurrenceKind(RK) ||
RecurrenceDescriptor::isFindIVRecurrenceKind(RK) ||
RecurrenceDescriptor::isMinMaxRecurrenceKind(RK))
return std::nullopt;
+ if (RecurrenceDescriptor::isFloatingPointRecurrenceKind(RK)) {
+ if (!RdxDesc.getFastMathFlags().allowReassoc())
+ return std::nullopt;
+ }
+
if (RdxDesc.IntermediateStore)
return std::nullopt;
diff --git a/llvm/test/Transforms/LoopUnroll/partial-unroll-reductions.ll b/llvm/test/Transforms/LoopUnroll/partial-unroll-reductions.ll
index 2d48d20ba9c5c..d7965b3061c70 100644
--- a/llvm/test/Transforms/LoopUnroll/partial-unroll-reductions.ll
+++ b/llvm/test/Transforms/LoopUnroll/partial-unroll-reductions.ll
@@ -319,27 +319,33 @@ define float @test_fadd_with_ressaoc(ptr %src, i64 %n, float %start) {
; CHECK-NEXT: br label %[[LOOP:.*]]
; CHECK: [[LOOP]]:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ 0, %[[ENTRY]] ], [ [[IV_NEXT_3:%.*]], %[[LOOP]] ]
-; CHECK-NEXT: [[RDX:%.*]] = phi float [ [[START]], %[[ENTRY]] ], [ [[RDX_NEXT_3:%.*]], %[[LOOP]] ]
+; CHECK-NEXT: [[RDX_1:%.*]] = phi float [ -0.000000e+00, %[[ENTRY]] ], [ [[RDX_NEXT_1:%.*]], %[[LOOP]] ]
+; CHECK-NEXT: [[RDX_2:%.*]] = phi float [ -0.000000e+00, %[[ENTRY]] ], [ [[RDX_NEXT_2:%.*]], %[[LOOP]] ]
+; CHECK-NEXT: [[RDX_3:%.*]] = phi float [ -0.000000e+00, %[[ENTRY]] ], [ [[RDX_NEXT_3:%.*]], %[[LOOP]] ]
+; CHECK-NEXT: [[RDX:%.*]] = phi float [ [[START]], %[[ENTRY]] ], [ [[RDX_NEXT:%.*]], %[[LOOP]] ]
; CHECK-NEXT: [[IV_NEXT:%.*]] = add nuw nsw i64 [[IV]], 1
; CHECK-NEXT: [[GEP_SRC:%.*]] = getelementptr float, ptr [[SRC]], i64 [[IV]]
; CHECK-NEXT: [[L:%.*]] = load float, ptr [[GEP_SRC]], align 1
-; CHECK-NEXT: [[RDX_NEXT:%.*]] = fadd float [[RDX]], [[L]]
+; CHECK-NEXT: [[RDX_NEXT]] = fadd reassoc float [[RDX]], [[L]]
; CHECK-NEXT: [[IV_NEXT_1:%.*]] = add nuw nsw i64 [[IV]], 2
; CHECK-NEXT: [[GEP_SRC_1:%.*]] = getelementptr float, ptr [[SRC]], i64 [[IV_NEXT]]
; CHECK-NEXT: [[L_1:%.*]] = load float, ptr [[GEP_SRC_1]], align 1
-; CHECK-NEXT: [[RDX_NEXT_1:%.*]] = fadd float [[RDX_NEXT]], [[L_1]]
+; CHECK-NEXT: [[RDX_NEXT_1]] = fadd reassoc float [[RDX_1]], [[L_1]]
; CHECK-NEXT: [[IV_NEXT_2:%.*]] = add nuw nsw i64 [[IV]], 3
; CHECK-NEXT: [[GEP_SRC_2:%.*]] = getelementptr float, ptr [[SRC]], i64 [[IV_NEXT_1]]
; CHECK-NEXT: [[L_2:%.*]] = load float, ptr [[GEP_SRC_2]], align 1
-; CHECK-NEXT: [[RDX_NEXT_2:%.*]] = fadd float [[RDX_NEXT_1]], [[L_2]]
+; CHECK-NEXT: [[RDX_NEXT_2]] = fadd reassoc float [[RDX_2]], [[L_2]]
; CHECK-NEXT: [[IV_NEXT_3]] = add nuw nsw i64 [[IV]], 4
; CHECK-NEXT: [[GEP_SRC_24:%.*]] = getelementptr float, ptr [[SRC]], i64 [[IV_NEXT_2]]
; CHECK-NEXT: [[L_24:%.*]] = load float, ptr [[GEP_SRC_24]], align 1
-; CHECK-NEXT: [[RDX_NEXT_3]] = fadd float [[RDX_NEXT_2]], [[L_24]]
+; CHECK-NEXT: [[RDX_NEXT_3]] = fadd reassoc float [[RDX_3]], [[L_24]]
; CHECK-NEXT: [[EC_3:%.*]] = icmp ne i64 [[IV_NEXT_3]], 1000
; CHECK-NEXT: br i1 [[EC_3]], label %[[LOOP]], label %[[EXIT:.*]]
; CHECK: [[EXIT]]:
-; CHECK-NEXT: [[RDX_NEXT_LCSSA:%.*]] = phi float [ [[RDX_NEXT_3]], %[[LOOP]] ]
+; CHECK-NEXT: [[RDX_NEXT_LCSSA1:%.*]] = phi float [ [[RDX_NEXT_3]], %[[LOOP]] ]
+; CHECK-NEXT: [[BIN_RDX:%.*]] = fadd reassoc float [[RDX_NEXT_1]], [[RDX_NEXT]]
+; CHECK-NEXT: [[BIN_RDX1:%.*]] = fadd reassoc float [[RDX_NEXT_2]], [[BIN_RDX]]
+; CHECK-NEXT: [[RDX_NEXT_LCSSA:%.*]] = fadd reassoc float [[RDX_NEXT_3]], [[BIN_RDX1]]
; CHECK-NEXT: ret float [[RDX_NEXT_LCSSA]]
;
entry:
@@ -351,13 +357,14 @@ loop:
%iv.next = add i64 %iv, 1
%gep.src = getelementptr float, ptr %src, i64 %iv
%l = load float, ptr %gep.src, align 1
- %rdx.next = fadd float %rdx, %l
+ %rdx.next = fadd reassoc float %rdx, %l
%ec = icmp ne i64 %iv.next, 1000
br i1 %ec, label %loop, label %exit
exit:
ret float %rdx.next
}
+
define i32 @test_smin(ptr %src, i64 %n) {
; CHECK-LABEL: define i32 @test_smin(
; CHECK-SAME: ptr [[SRC:%.*]], i64 [[N:%.*]]) {
diff --git a/llvm/test/Transforms/LoopUnroll/runtime-unroll-reductions.ll b/llvm/test/Transforms/LoopUnroll/runtime-unroll-reductions.ll
index a5ac2cf46653d..591401edc143a 100644
--- a/llvm/test/Transforms/LoopUnroll/runtime-unroll-reductions.ll
+++ b/llvm/test/Transforms/LoopUnroll/runtime-unroll-reductions.ll
@@ -220,6 +220,137 @@ exit:
ret i32 %res
}
+define float @test_fadd_reduction(ptr %a, i64 %n) {
+; CHECK-LABEL: define float @test_fadd_reduction(
+; CHECK-SAME: ptr [[A:%.*]], i64 [[N:%.*]]) {
+; CHECK-NEXT: [[ENTRY:.*]]:
+; CHECK-NEXT: [[TMP0:%.*]] = add i64 [[N]], -1
+; CHECK-NEXT: [[XTRAITER:%.*]] = and i64 [[N]], 1
+; CHECK-NEXT: [[TMP1:%.*]] = icmp ult i64 [[TMP0]], 1
+; CHECK-NEXT: br i1 [[TMP1]], label %[[LOOP_EPIL_PREHEADER:.*]], label %[[ENTRY_NEW:.*]]
+; CHECK: [[ENTRY_NEW]]:
+; CHECK-NEXT: [[UNROLL_ITER:%.*]] = sub i64 [[N]], [[XTRAITER]]
+; CHECK-NEXT: br label %[[LOOP:.*]]
+; CHECK: [[LOOP]]:
+; CHECK-NEXT: [[IV:%.*]] = phi i64 [ 0, %[[ENTRY_NEW]] ], [ [[IV_NEXT_1:%.*]], %[[LOOP]] ]
+; CHECK-NEXT: [[RDX_1:%.*]] = phi float [ -0.000000e+00, %[[ENTRY_NEW]] ], [ [[RDX_NEXT_1:%.*]], %[[LOOP]] ]
+; CHECK-NEXT: [[RDX:%.*]] = phi float [ 0.000000e+00, %[[ENTRY_NEW]] ], [ [[RDX_NEXT:%.*]], %[[LOOP]] ]
+; CHECK-NEXT: [[NITER:%.*]] = phi i64 [ 0, %[[ENTRY_NEW]] ], [ [[NITER_NEXT_1:%.*]], %[[LOOP]] ]
+; CHECK-NEXT: [[GEP_A:%.*]] = getelementptr inbounds nuw float, ptr [[A]], i64 [[IV]]
+; CHECK-NEXT: [[TMP2:%.*]] = load float, ptr [[GEP_A]], align 16
+; CHECK-NEXT: [[RDX_NEXT]] = fadd reassoc float [[RDX]], [[TMP2]]
+; CHECK-NEXT: [[IV_NEXT:%.*]] = add nuw nsw i64 [[IV]], 1
+; CHECK-NEXT: [[GEP_A_1:%.*]] = getelementptr inbounds nuw float, ptr [[A]], i64 [[IV_NEXT]]
+; CHECK-NEXT: [[TMP3:%.*]] = load float, ptr [[GEP_A_1]], align 16
+; CHECK-NEXT: [[RDX_NEXT_1]] = fadd reassoc float [[RDX_1]], [[TMP3]]
+; CHECK-NEXT: [[IV_NEXT_1]] = add nuw nsw i64 [[IV]], 2
+; CHECK-NEXT: [[NITER_NEXT_1]] = add i64 [[NITER]], 2
+; CHECK-NEXT: [[NITER_NCMP_1:%.*]] = icmp eq i64 [[NITER_NEXT_1]], [[UNROLL_ITER]]
+; CHECK-NEXT: br i1 [[NITER_NCMP_1]], label %[[EXIT_UNR_LCSSA:.*]], label %[[LOOP]], !llvm.loop [[LOOP5:![0-9]+]]
+; CHECK: [[EXIT_UNR_LCSSA]]:
+; CHECK-NEXT: [[RES_PH:%.*]] = phi float [ [[RDX_NEXT_1]], %[[LOOP]] ]
+; CHECK-NEXT: [[IV_UNR:%.*]] = phi i64 [ [[IV_NEXT_1]], %[[LOOP]] ]
+; CHECK-NEXT: [[RDX_UNR:%.*]] = phi float [ [[RDX_NEXT_1]], %[[LOOP]] ]
+; CHECK-NEXT: [[BIN_RDX:%.*]] = fadd reassoc float [[RDX_NEXT_1]], [[RDX_NEXT]]
+; CHECK-NEXT: [[LCMP_MOD:%.*]] = icmp ne i64 [[XTRAITER]], 0
+; CHECK-NEXT: br i1 [[LCMP_MOD]], label %[[LOOP_EPIL_PREHEADER]], label %[[EXIT:.*]]
+; CHECK: [[LOOP_EPIL_PREHEADER]]:
+; CHECK-NEXT: [[IV_EPIL_INIT:%.*]] = phi i64 [ 0, %[[ENTRY]] ], [ [[IV_UNR]], %[[EXIT_UNR_LCSSA]] ]
+; CHECK-NEXT: [[RDX_EPIL_INIT:%.*]] = phi float [ 0.000000e+00, %[[ENTRY]] ], [ [[BIN_RDX]], %[[EXIT_UNR_LCSSA]] ]
+; CHECK-NEXT: [[LCMP_MOD2:%.*]] = icmp ne i64 [[XTRAITER]], 0
+; CHECK-NEXT: call void @llvm.assume(i1 [[LCMP_MOD2]])
+; CHECK-NEXT: br label %[[LOOP_EPIL:.*]]
+; CHECK: [[LOOP_EPIL]]:
+; CHECK-NEXT: [[GEP_A_EPIL:%.*]] = getelementptr inbounds nuw float, ptr [[A]], i64 [[IV_EPIL_INIT]]
+; CHECK-NEXT: [[TMP4:%.*]] = load float, ptr [[GEP_A_EPIL]], align 16
+; CHECK-NEXT: [[RDX_NEXT_EPIL:%.*]] = fadd reassoc float [[RDX_EPIL_INIT]], [[TMP4]]
+; CHECK-NEXT: br label %[[EXIT]]
+; CHECK: [[EXIT]]:
+; CHECK-NEXT: [[RES:%.*]] = phi float [ [[BIN_RDX]], %[[EXIT_UNR_LCSSA]] ], [ [[RDX_NEXT_EPIL]], %[[LOOP_EPIL]] ]
+; CHECK-NEXT: ret float [[RES]]
+;
+entry:
+ br label %loop
+
+loop:
+ %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+ %rdx = phi float [ 0.0, %entry ], [ %rdx.next, %loop ]
+ %gep.a = getelementptr inbounds nuw float, ptr %a, i64 %iv
+ %1 = load float, ptr %gep.a, align 16
+ %rdx.next = fadd reassoc float %rdx, %1
+ %iv.next = add nuw nsw i64 %iv, 1
+ %ec = icmp eq i64 %iv.next, %n
+ br i1 %ec, label %exit, label %loop, !llvm.loop !0
+
+exit:
+ %res = phi float [ %rdx.next, %loop ]
+ ret float %res
+}
+
+define float @test_fadd_no_reassoc(ptr %a, i64 %n) {
+; CHECK-LABEL: define float @test_fadd_no_reassoc(
+; CHECK-SAME: ptr [[A:%.*]], i64 [[N:%.*]]) {
+; CHECK-NEXT: [[ENTRY:.*]]:
+; CHECK-NEXT: [[TMP0:%.*]] = add i64 [[N]], -1
+; CHECK-NEXT: [[XTRAITER:%.*]] = and i64 [[N]], 1
+; CHECK-NEXT: [[TMP1:%.*]] = icmp ult i64 [[TMP0]], 1
+; CHECK-NEXT: br i1 [[TMP1]], label %[[LOOP_EPIL_PREHEADER:.*]], label %[[ENTRY_NEW:.*]]
+; CHECK: [[ENTRY_NEW]]:
+; CHECK-NEXT: [[UNROLL_ITER:%.*]] = sub i64 [[N]], [[XTRAITER]]
+; CHECK-NEXT: br label %[[LOOP:.*]]
+; CHECK: [[LOOP]]:
+; CHECK-NEXT: [[IV:%.*]] = phi i64 [ 0, %[[ENTRY_NEW]] ], [ [[IV_NEXT_1:%.*]], %[[LOOP]] ]
+; CHECK-NEXT: [[RDX:%.*]] = phi float [ 0.000000e+00, %[[ENTRY_NEW]] ], [ [[RDX_NEXT_1:%.*]], %[[LOOP]] ]
+; CHECK-NEXT: [[NITER:%.*]] = phi i64 [ 0, %[[ENTRY_NEW]] ], [ [[NITER_NEXT_1:%.*]], %[[LOOP]] ]
+; CHECK-NEXT: [[GEP_A:%.*]] = getelementptr inbounds nuw float, ptr [[A]], i64 [[IV]]
+; CHECK-NEXT: [[TMP2:%.*]] = load float, ptr [[GEP_A]], align 16
+; CHECK-NEXT: [[RDX_NEXT:%.*]] = fadd float [[RDX]], [[TMP2]]
+; CHECK-NEXT: [[IV_NEXT:%.*]] = add nuw nsw i64 [[IV]], 1
+; CHECK-NEXT: [[GEP_A_1:%.*]] = getelementptr inbounds nuw float, ptr [[A]], i64 [[IV_NEXT]]
+; CHECK-NEXT: [[TMP3:%.*]] = load float, ptr [[GEP_A_1]], align 16
+; CHECK-NEXT: [[RDX_NEXT_1]] = fadd float [[RDX_NEXT]], [[TMP3]]
+; CHECK-NEXT: [[IV_NEXT_1]] = add nuw nsw i64 [[IV]], 2
+; CHECK-NEXT: [[NITER_NEXT_1]] = add i64 [[NITER]], 2
+; CHECK-NEXT: [[NITER_NCMP_1:%.*]] = icmp eq i64 [[NITER_NEXT_1]], [[UNROLL_ITER]]
+; CHECK-NEXT: br i1 [[NITER_NCMP_1]], label %[[EXIT_UNR_LCSSA:.*]], label %[[LOOP]], !llvm.loop [[LOOP6:![0-9]+]]
+; CHECK: [[EXIT_UNR_LCSSA]]:
+; CHECK-NEXT: [[RES_PH:%.*]] = phi float [ [[RDX_NEXT_1]], %[[LOOP]] ]
+; CHECK-NEXT: [[IV_UNR:%.*]] = phi i64 [ [[IV_NEXT_1]], %[[LOOP]] ]
+; CHECK-NEXT: [[RDX_UNR:%.*]] = phi float [ [[RDX_NEXT_1]], %[[LOOP]] ]
+; CHECK-NEXT: [[LCMP_MOD:%.*]] = icmp ne i64 [[XTRAITER]], 0
+; CHECK-NEXT: br i1 [[LCMP_MOD]], label %[[LOOP_EPIL_PREHEADER]], label %[[EXIT:.*]]
+; CHECK: [[LOOP_EPIL_PREHEADER]]:
+; CHECK-NEXT: [[IV_EPIL_INIT:%.*]] = phi i64 [ 0, %[[ENTRY]] ], [ [[IV_UNR]], %[[EXIT_UNR_LCSSA]] ]
+; CHECK-NEXT: [[RDX_EPIL_INIT:%.*]] = phi float [ 0.000000e+00, %[[ENTRY]] ], [ [[RDX_UNR]], %[[EXIT_UNR_LCSSA]] ]
+; CHECK-NEXT: [[LCMP_MOD2:%.*]] = icmp ne i64 [[XTRAITER]], 0
+; CHECK-NEXT: call void @llvm.assume(i1 [[LCMP_MOD2]])
+; CHECK-NEXT: br label %[[LOOP_EPIL:.*]]
+; CHECK: [[LOOP_EPIL]]:
+; CHECK-NEXT: [[GEP_A_EPIL:%.*]] = getelementptr inbounds nuw float, ptr [[A]], i64 [[IV_EPIL_INIT]]
+; CHECK-NEXT: [[TMP4:%.*]] = load float, ptr [[GEP_A_EPIL]], align 16
+; CHECK-NEXT: [[RDX_NEXT_EPIL:%.*]] = fadd float [[RDX_EPIL_INIT]], [[TMP4]]
+; CHECK-NEXT: br label %[[EXIT]]
+; CHECK: [[EXIT]]:
+; CHECK-NEXT: [[RES:%.*]] = phi float [ [[RES_PH]], %[[EXIT_UNR_LCSSA]] ], [ [[RDX_NEXT_EPIL]], %[[LOOP_EPIL]] ]
+; CHECK-NEXT: ret float [[RES]]
+;
+entry:
+ br label %loop
+
+loop:
+ %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+ %rdx = phi float [ 0.0, %entry ], [ %rdx.next, %loop ]
+ %gep.a = getelementptr inbounds nuw float, ptr %a, i64 %iv
+ %1 = load float, ptr %gep.a, align 16
+ %rdx.next = fadd float %rdx, %1
+ %iv.next = add nuw nsw i64 %iv, 1
+ %ec = icmp eq i64 %iv.next, %n
+ br i1 %ec, label %exit, label %loop, !llvm.loop !0
+
+exit:
+ %res = phi float [ %rdx.next, %loop ]
+ ret float %res
+}
!0 = distinct !{!0, !1}
@@ -234,4 +365,6 @@ exit:
; CHECK: [[LOOP2]] = distinct !{[[LOOP2]], [[META1]]}
; CHECK: [[LOOP3]] = distinct !{[[LOOP3]], [[META1]]}
; CHECK: [[LOOP4]] = distinct !{[[LOOP4]], [[META1]]}
+; CHECK: [[LOOP5]] = distinct !{[[LOOP5]], [[META1]]}
+; CHECK: [[LOOP6]] = distinct !{[[LOOP6]], [[META1]]}
;.
>From 72842324d051adedbff932d7ea7c04ec43a88eba Mon Sep 17 00:00:00 2001
From: Julian Nagele <j_nagele at apple.com>
Date: Thu, 20 Nov 2025 17:39:27 +0000
Subject: [PATCH 2/2] fixup! [LoopUnroll] Introduce parallel accumulators when
unrolling FP reductions.
---
llvm/lib/Transforms/Utils/LoopUnroll.cpp | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/llvm/lib/Transforms/Utils/LoopUnroll.cpp b/llvm/lib/Transforms/Utils/LoopUnroll.cpp
index d3d7faf6ab7ff..fe68184cd6d48 100644
--- a/llvm/lib/Transforms/Utils/LoopUnroll.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUnroll.cpp
@@ -1258,17 +1258,13 @@ llvm::canParallelizeReductionWhenUnrolling(PHINode &Phi, Loop *L,
RecurKind RK = RdxDesc.getRecurrenceKind();
// Skip unsupported reductions.
// TODO: Handle additional reductions, including min-max reductions.
- if (!(RecurrenceDescriptor::isIntegerRecurrenceKind(RK) ||
- RecurrenceDescriptor::isFloatingPointRecurrenceKind(RK)) ||
- RecurrenceDescriptor::isAnyOfRecurrenceKind(RK) ||
+ if (RecurrenceDescriptor::isAnyOfRecurrenceKind(RK) ||
RecurrenceDescriptor::isFindIVRecurrenceKind(RK) ||
RecurrenceDescriptor::isMinMaxRecurrenceKind(RK))
return std::nullopt;
- if (RecurrenceDescriptor::isFloatingPointRecurrenceKind(RK)) {
- if (!RdxDesc.getFastMathFlags().allowReassoc())
+ if (RdxDesc.hasExactFPMath())
return std::nullopt;
- }
if (RdxDesc.IntermediateStore)
return std::nullopt;
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