[llvm] Optimize fptrunc(x)>=C1 --> x>=C2 (PR #99475)
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Mon Jul 14 06:19:36 PDT 2025
https://github.com/kissholic updated https://github.com/llvm/llvm-project/pull/99475
>From 5fabe6378045ba2082e200a9462fe32fd2e41339 Mon Sep 17 00:00:00 2001
From: kissholic <kissholicovo at outlook.com>
Date: Sun, 16 Mar 2025 16:36:50 +0800
Subject: [PATCH 1/2] Optimize fptrunc(x)>=C1 --> x>=C2
---
.../InstCombine/InstCombineCompares.cpp | 99 +++
.../InstCombine/fold-fcmp-trunc-tmp.ll | 596 ++++++++++++++++++
2 files changed, 695 insertions(+)
create mode 100644 llvm/test/Transforms/InstCombine/fold-fcmp-trunc-tmp.ll
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 76020d2b1dbf4..065fd88c19b85 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -8031,6 +8031,101 @@ static Instruction *foldFCmpReciprocalAndZero(FCmpInst &I, Instruction *LHSI,
return new FCmpInst(Pred, LHSI->getOperand(1), RHSC, "", &I);
}
+
+// Fold fptrunc(x) < constant --> x < constant if possible.
+static Instruction *foldFCmpFpTrunc(FCmpInst &I, Instruction *LHSI,
+ Constant *RHSC) {
+ FCmpInst::Predicate Pred = I.getPredicate();
+ bool RoundDown = false;
+
+ if (Pred == FCmpInst::FCMP_OGE || Pred == FCmpInst::FCMP_UGE ||
+ Pred == FCmpInst::FCMP_OLT || Pred == FCmpInst::FCMP_ULT)
+ RoundDown = true;
+ else if (Pred == FCmpInst::FCMP_OGT || Pred == FCmpInst::FCMP_UGT ||
+ Pred == FCmpInst::FCMP_OLE || Pred == FCmpInst::FCMP_ULE)
+ RoundDown = false;
+ else
+ return nullptr;
+
+ const APFloat *RValue;
+ if (!match(RHSC, m_APFloat(RValue)))
+ return nullptr;
+
+ // RHSC should not be nan or infinity.
+ if (RValue->isNaN() || RValue->isInfinity())
+ return nullptr;
+
+ Type *LType = LHSI->getOperand(0)->getType();
+ Type *RType = RHSC->getType();
+ Type *LEleType = LType->getScalarType();
+ Type *REleType = RType->getScalarType();
+
+ APFloat NextRValue = *RValue;
+ NextRValue.next(RoundDown);
+
+ // Promote 'RValue' and 'NextRValue' to 'LType'.
+ APFloat ExtRValue = *RValue;
+ APFloat ExtNextRValue = NextRValue;
+ bool lossInfo;
+ ExtRValue.convert(LEleType->getFltSemantics(), APFloat::rmNearestTiesToEven,
+ &lossInfo);
+ ExtNextRValue.convert(LEleType->getFltSemantics(),
+ APFloat::rmNearestTiesToEven, &lossInfo);
+
+ // The (negative) maximum of 'RValue' may become infinity when rounded up
+ // (down). Set the limit of 'ExtNextRValue'.
+ if (NextRValue.isInfinity())
+ ExtNextRValue = scalbn(ExtRValue, 1, APFloat::rmNearestTiesToEven);
+
+ // Binary search to find the maximal (or minimal) value after 'RValue'
+ // promotion. 'RValue' should obey normal comparison rules, which means nan or
+ // inf is not allowed here.
+ APFloat RoundValue{LEleType->getFltSemantics()};
+
+ APFloat LowBound = RoundDown ? ExtNextRValue : ExtRValue;
+ APFloat UpBound = RoundDown ? ExtRValue : ExtNextRValue;
+
+ auto IsRoundingFound = [](const APFloat &LowBound, const APFloat &UpBound) {
+ APFloat UpBoundNext = UpBound;
+ UpBoundNext.next(true);
+ return LowBound == UpBoundNext;
+ };
+
+ auto EqualRValueAfterTrunc = [&](const APFloat &ExtValue) {
+ APFloat TruncValue = ExtValue;
+ TruncValue.convert(REleType->getFltSemantics(),
+ APFloat::rmNearestTiesToEven, &lossInfo);
+ return TruncValue == *RValue;
+ };
+
+ while (true) {
+ // Finish searching when 'LowBound' is next to 'UpBound'.
+ if (IsRoundingFound(LowBound, UpBound)) {
+ RoundValue = RoundDown ? UpBound : LowBound;
+ break;
+ }
+
+ APFloat Mid = scalbn(LowBound + UpBound, -1, APFloat::rmNearestTiesToEven);
+ bool EqualRValue = EqualRValueAfterTrunc(Mid);
+
+ // 'EqualRValue' indicates whether Mid is qualified to be the final round
+ // value. if 'EqualRValue' == true, 'Mid' might be the final round value
+ // if 'RoundDown' == true, 'UpBound' can't be the final round value
+ // if 'RoudnDown' == false, 'DownBound' can't be the final round value
+ // if 'EqualRValue' == false, 'Mid' can't be the final round value
+ // if 'RoundDown' == true, 'DownBound' can't be the final round value
+ // if 'RoundDown' == false, 'UpBound' can't be the final round value
+ if (EqualRValue == RoundDown) {
+ UpBound = Mid;
+ } else {
+ LowBound = Mid;
+ }
+ }
+
+ return new FCmpInst(Pred, LHSI->getOperand(0),
+ ConstantFP::get(LType, RoundValue), "", &I);
+}
+
/// Optimize fabs(X) compared with zero.
static Instruction *foldFabsWithFcmpZero(FCmpInst &I, InstCombinerImpl &IC) {
Value *X;
@@ -8522,6 +8617,10 @@ Instruction *InstCombinerImpl::visitFCmpInst(FCmpInst &I) {
cast<LoadInst>(LHSI), GEP, GV, I))
return Res;
break;
+ case Instruction::FPTrunc:
+ if (Instruction *NV = foldFCmpFpTrunc(I, LHSI, RHSC))
+ return NV;
+ break;
}
}
diff --git a/llvm/test/Transforms/InstCombine/fold-fcmp-trunc-tmp.ll b/llvm/test/Transforms/InstCombine/fold-fcmp-trunc-tmp.ll
new file mode 100644
index 0000000000000..1d3dab8728a49
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/fold-fcmp-trunc-tmp.ll
@@ -0,0 +1,596 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -passes=instcombine -S < %s | FileCheck %s
+
+
+define i1 @fcmp_trunc(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp oge double [[TMP0]], 0x4058FFFFF0000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp oge float %trunc, 1.000000e+02
+ ret i1 %result
+}
+
+define i1 @fcmp_trunc_ult(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_ult(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp ult double [[TMP0]], 0x4068FFFFF0000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp ult float %trunc, 2.000000e+02
+ ret i1 %result
+}
+
+define i1 @fcmp_trunc_ole(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_ole(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp ole double [[TMP0]], 0x4072C00010000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp ole float %trunc, 3.000000e+02
+ ret i1 %result
+}
+
+define i1 @fcmp_trunc_ogt(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_ogt(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp ogt double [[TMP0]], 0x4079000010000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp ogt float %trunc, 4.000000e+02
+ ret i1 %result
+}
+
+define i1 @fcmp_trunc_zero(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_zero(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp oge double [[TMP0]], 0xB690000000000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp oge float %trunc, 0.000000
+ ret i1 %result
+}
+
+define i1 @fcmp_trunc_with_nnan(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_with_nnan(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp nnan oge double [[TMP0]], 0x4058FFFFF0000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp nnan oge float %trunc, 1.000000e+02
+ ret i1 %result
+}
+
+define i1 @fcmp_trunc_with_ninf(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_with_ninf(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp ninf oge double [[TMP0]], 0x4058FFFFF0000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp ninf oge float %trunc, 1.000000e+02
+ ret i1 %result
+}
+
+define i1 @fcmp_trunc_with_nsz(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_with_nsz(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp nsz oge double [[TMP0]], 0x4058FFFFF0000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp nsz oge float %trunc, 1.000000e+02
+ ret i1 %result
+}
+
+define i1 @fcmp_trunc_with_reassoc(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_with_reassoc(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp reassoc oge double [[TMP0]], 0x4058FFFFF0000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp reassoc oge float %trunc, 1.000000e+02
+ ret i1 %result
+}
+
+define i1 @fcmp_trunc_with_fast(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_with_fast(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp fast oge double [[TMP0]], 0x4058FFFFF0000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp fast oge float %trunc, 1.000000e+02
+ ret i1 %result
+}
+
+define <4 x i1> @fcmp_vec_trunc(<4 x double> %0) {
+; CHECK-LABEL: define <4 x i1> @fcmp_vec_trunc(
+; CHECK-SAME: <4 x double> [[TMP0:%.*]]) {
+; CHECK-NEXT: [[CMP:%.*]] = fcmp olt <4 x double> [[TMP0]], splat (double 0x3FEFFFFFF0000000)
+; CHECK-NEXT: ret <4 x i1> [[CMP]]
+;
+ %vec = fptrunc <4 x double> %0 to <4 x float>
+ %cmp = fcmp olt <4 x float> %vec, <float 1.0, float 1.0, float 1.0, float 1.0>
+ ret <4 x i1> %cmp
+}
+
+define <1 x i1> @fcmp_vec_trunc_scalar(<1 x double> %0) {
+; CHECK-LABEL: define <1 x i1> @fcmp_vec_trunc_scalar(
+; CHECK-SAME: <1 x double> [[TMP0:%.*]]) {
+; CHECK-NEXT: [[CMP:%.*]] = fcmp fast olt <1 x double> [[TMP0]], splat (double 0x3FEFFFFFF0000000)
+; CHECK-NEXT: ret <1 x i1> [[CMP]]
+;
+ %vec = fptrunc <1 x double> %0 to <1 x float>
+ %cmp = fcmp fast olt <1 x float> %vec, <float 1.0>
+ ret <1 x i1> %cmp
+}
+
+define i1 @fcmp_trunc_fp128(fp128 %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_fp128(
+; CHECK-SAME: fp128 [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp fast oge fp128 [[TMP0]], 0xL000000000000000040058FFFFF000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc fp128 %0 to float
+ %result = fcmp fast oge float %trunc, 1.000000e+02
+ ret i1 %result
+}
+
+define i1 @fcmp_trunc_x86_fp80(x86_fp80 %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_x86_fp80(
+; CHECK-SAME: x86_fp80 [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp fast oge x86_fp80 [[TMP0]], 0xK4005C7FFFF8000000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc x86_fp80 %0 to float
+ %result = fcmp fast oge float %trunc, 1.000000e+02
+ ret i1 %result
+}
+
+define i1 @fcmp_trunc_ppc_fp128(ppc_fp128 %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_ppc_fp128(
+; CHECK-SAME: ppc_fp128 [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp fast oge ppc_fp128 [[TMP0]], 0xM4058FFFFF0000000BD00000000000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc ppc_fp128 %0 to float
+ %result = fcmp fast oge float %trunc, 1.000000e+02
+ ret i1 %result
+}
+
+define i1 @fcmp_trunc_nan(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_nan(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: ret i1 false
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp oge float %trunc, 0x7FF8000000000000
+ ret i1 %result
+}
+
+; denomalized 0x00000001
+define i1 @fcmp_trunc_d1(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_d1(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp oge double [[TMP0]], 0x3690000000000001
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp oge float %trunc, 1.40129846432481707092372958328991613128026194187651577175706828388979108268586060148663818836212158203125e-45
+ ret i1 %result
+}
+
+; denomalized 0x00000001 ole
+define i1 @fcmp_trunc_d1_ole(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_d1_ole(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp ole double [[TMP0]], 0x36A7FFFFFFFFFFFF
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp ole float %trunc, 1.40129846432481707092372958328991613128026194187651577175706828388979108268586060148663818836212158203125e-45
+ ret i1 %result
+}
+
+; denomalized 0x00000002
+define i1 @fcmp_trunc_d2(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_d2(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp oge double [[TMP0]], 0x36A8000000000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp oge float %trunc, 2.8025969286496341418474591665798322625605238837530315435141365677795821653717212029732763767242431640625e-45
+ ret i1 %result
+}
+
+; denomalized 0x7fffff
+define i1 @fcmp_trunc_d3(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_d3(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp ogt double [[TMP0]], 0x380FFFFFDFFFFFFF
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp ogt float %trunc, 1.175494210692441075487029444849287348827052428745893333857174530571588870475618904265502351336181163787841796875e-38
+ ret i1 %result
+}
+
+; denomalized 0x80000001
+define i1 @fcmp_trunc_d4(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_d4(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp ogt double [[TMP0]], 0xB690000000000001
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp ogt float %trunc, -1.40129846432481707092372958328991613128026194187651577175706828388979108268586060148663818836212158203125e-45
+ ret i1 %result
+}
+
+; denomalized 0x80000001
+define i1 @fcmp_trunc_d5(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_d5(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp olt double [[TMP0]], 0xB80FFFFFDFFFFFFF
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp olt float %trunc, -1.175494210692441075487029444849287348827052428745893333857174530571588870475618904265502351336181163787841796875e-38
+ ret i1 %result
+}
+
+
+; +0
+define i1 @fcmp_trunc_p0(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_p0(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp oge double [[TMP0]], 0xB690000000000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp oge float %trunc, 0x00000000
+ ret i1 %result
+}
+
+
+; -0
+define i1 @fcmp_trunc_n0(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_n0(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp ogt double [[TMP0]], 0x3690000000000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp ogt float %trunc, 0x8000000000000000
+ ret i1 %result
+}
+
+
+; max representable
+define i1 @fcmp_trunc_mx(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_mx(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp ogt double [[TMP0]], 0x47EFFFFFEFFFFFFF
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp ogt float %trunc, 0x47EFFFFFE0000000
+ ret i1 %result
+}
+
+; min representable
+define i1 @fcmp_trunc_mn(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_mn(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp olt double [[TMP0]], 0xC7EFFFFFEFFFFFFF
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp olt float %trunc, -3.4028234663852885981170418348451692544e38
+ ret i1 %result
+}
+
+
+define i1 @fcmp_trunc_literal_nan(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_literal_nan(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: ret i1 false
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp oge float %trunc, 0x7FF8000000000000
+ ret i1 %result
+}
+
+define i1 @fcmp_trunc_literal_positive_inf(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_literal_positive_inf(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[TRUNC:%.*]] = fptrunc double [[TMP0]] to float
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp oeq float [[TRUNC]], 0x7FF0000000000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp oge float %trunc, 0x7FF0000000000000
+ ret i1 %result
+}
+
+
+define i1 @fcmp_trunc_literal_negative_inf(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_literal_negative_inf(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[TRUNC:%.*]] = fptrunc double [[TMP0]] to float
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp uno float [[TRUNC]], 0.000000e+00
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp ult float %trunc, 0xFFF0000000000000
+ ret i1 %result
+}
+
+
+define i1 @fcmp_trunc_nan_ugt(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_nan_ugt(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: ret i1 true
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp ugt float %trunc, 0x7FF8000000000000
+ ret i1 %result
+}
+
+define i1 @fcmp_trunc_inf_uge(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_inf_uge(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[TRUNC:%.*]] = fptrunc double [[TMP0]] to float
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp ueq float [[TRUNC]], 0x7FF0000000000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp uge float %trunc, 0x7FF0000000000000
+ ret i1 %result
+}
+
+
+define i1 @fcmp_trunc_ninf_olt(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_ninf_olt(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: ret i1 false
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp olt float %trunc, 0xFFF0000000000000
+ ret i1 %result
+}
+
+
+define i1 @fcmp_trunc_uge(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_uge(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp uge double [[TMP0]], 0x405EBFFFF0000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp uge float %trunc, 123.0
+ ret i1 %result
+}
+
+
+define i1 @fcmp_trunc_neg_uge(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_neg_uge(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp uge double [[TMP0]], 0xC05EC00010000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp uge float %trunc, -123.0
+ ret i1 %result
+}
+
+
+define i1 @fcmp_trunc_oge(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_oge(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp oge double [[TMP0]], 0x405EBFFFF0000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp oge float %trunc, 123.0
+ ret i1 %result
+}
+
+
+define i1 @fcmp_trunc_neg_oge(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_neg_oge(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp oge double [[TMP0]], 0xC05EC00010000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp oge float %trunc, -123.0
+ ret i1 %result
+}
+
+
+define i1 @fcmp_trunc_ugt(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_ugt(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp ugt double [[TMP0]], 0x40FE0F3010000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp ugt float %trunc, 123123.0
+ ret i1 %result
+}
+
+
+define i1 @fcmp_trunc_neg_ugt(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_neg_ugt(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp ugt double [[TMP0]], 0xC0FE1B8FF0000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp ugt float %trunc, -123321.0
+ ret i1 %result
+}
+
+
+define i1 @fcmp_trunc_neg_ogt(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_neg_ogt(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp ogt double [[TMP0]], 0xC0FE1B8FF0000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp ogt float %trunc, -123321.0
+ ret i1 %result
+}
+
+
+
+define i1 @fcmp_trunc_ule(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_ule(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp ule double [[TMP0]], 0x408ED80010000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp ule float %trunc, 987.0
+ ret i1 %result
+}
+
+
+
+define i1 @fcmp_trunc_neg_ule(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_neg_ule(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp ule double [[TMP0]], 0xC088A7FFF0000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp ule float %trunc, -789.0
+ ret i1 %result
+}
+
+
+
+define i1 @fcmp_trunc_neg_ole(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_neg_ole(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp ole double [[TMP0]], 0xC088A7FFF0000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp ole float %trunc, -789.0
+ ret i1 %result
+}
+
+
+define i1 @fcmp_trunc_neg_ult(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_neg_ult(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp ult double [[TMP0]], 0xC088A80010000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp ult float %trunc, -789.0
+ ret i1 %result
+}
+
+
+
+define i1 @fcmp_trunc_olt(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_olt(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp olt double [[TMP0]], 0x408ED7FFF0000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp olt float %trunc, 987.0
+ ret i1 %result
+}
+
+
+
+define i1 @fcmp_trunc_neg_olt(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_neg_olt(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp olt double [[TMP0]], 0xC088A80010000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp olt float %trunc, -789.0
+ ret i1 %result
+}
+
+
+define i1 @fcmp_trunc_neg_nsz_uge(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_neg_nsz_uge(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp nsz uge double [[TMP0]], 0xC05EC00010000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp nsz uge float %trunc, -123.0
+ ret i1 %result
+}
+
+
+
+define i1 @fcmp_trunc_reassoc_ugt(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_reassoc_ugt(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp reassoc ugt double [[TMP0]], 0x40889F8210000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp reassoc ugt float %trunc, 787.9384765625
+ ret i1 %result
+}
+
+
+define i1 @fcmp_trunc_neg_reassoc_ugt(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_neg_reassoc_ugt(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp reassoc ugt double [[TMP0]], 0xC0889F81F0000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp reassoc ugt float %trunc, -787.9384765625
+ ret i1 %result
+}
+
+
+
+define i1 @fcmp_trunc_fast_ult(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_fast_ult(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp fast uge double [[TMP0]], 0x40F8E8E010000001
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp fast uge float %trunc, 102030.0078125
+ ret i1 %result
+}
+
+
+define i1 @fcmp_trunc_neg_fast_ult(double %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_neg_fast_ult(
+; CHECK-SAME: double [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp fast uge double [[TMP0]], 0xC0F8E8E02FFFFFFF
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc double %0 to float
+ %result = fcmp fast uge float %trunc, -102030.0078125
+ ret i1 %result
+}
+
+
>From 8d1539a0d81892e7638916884dce82fc45980d87 Mon Sep 17 00:00:00 2001
From: kissholic <kissholicovo at outlook.com>
Date: Wed, 9 Jul 2025 21:01:58 +0800
Subject: [PATCH 2/2] Optimize fptrunc(x)>=C1 --> x>=C2
---
.../InstCombine/InstCombineCompares.cpp | 132 +++++++++---------
...d-fcmp-trunc-tmp.ll => fold-fcmp-trunc.ll} | 82 ++++++++++-
2 files changed, 146 insertions(+), 68 deletions(-)
rename llvm/test/Transforms/InstCombine/{fold-fcmp-trunc-tmp.ll => fold-fcmp-trunc.ll} (87%)
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 065fd88c19b85..a73aa478f13e8 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -11,6 +11,7 @@
//===----------------------------------------------------------------------===//
#include "InstCombineInternal.h"
+#include "llvm/ADT/APFloat.h"
#include "llvm/ADT/APSInt.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/Statistic.h"
@@ -21,8 +22,10 @@
#include "llvm/Analysis/Utils/Local.h"
#include "llvm/Analysis/VectorUtils.h"
#include "llvm/IR/ConstantRange.h"
+#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/InstrTypes.h"
+#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/Support/KnownBits.h"
@@ -8031,10 +8034,16 @@ static Instruction *foldFCmpReciprocalAndZero(FCmpInst &I, Instruction *LHSI,
return new FCmpInst(Pred, LHSI->getOperand(1), RHSC, "", &I);
}
-
-// Fold fptrunc(x) < constant --> x < constant if possible.
-static Instruction *foldFCmpFpTrunc(FCmpInst &I, Instruction *LHSI,
- Constant *RHSC) {
+// Transform 'fptrunc(x) cmp C' to 'x cmp ext(C)' if possible.
+// Patterns include:
+// fptrunc(x) < C --> x < ext(C)
+// fptrunc(x) <= C --> x <= ext(C)
+// fptrunc(x) > C --> x > ext(C)
+// fptrunc(x) >= C --> x >= ext(C)
+// where 'ext(C)' is the extension of 'C' to the type of 'x' with a small bias
+// due to precision loss.
+static Instruction *foldFCmpFpTrunc(FCmpInst &I, const Instruction &FPTrunc,
+ const Constant &C) {
FCmpInst::Predicate Pred = I.getPredicate();
bool RoundDown = false;
@@ -8047,83 +8056,74 @@ static Instruction *foldFCmpFpTrunc(FCmpInst &I, Instruction *LHSI,
else
return nullptr;
- const APFloat *RValue;
- if (!match(RHSC, m_APFloat(RValue)))
+ const APFloat *CValue;
+ if (!match(&C, m_APFloat(CValue)))
return nullptr;
- // RHSC should not be nan or infinity.
- if (RValue->isNaN() || RValue->isInfinity())
+ if (CValue->isNaN() || CValue->isInfinity())
return nullptr;
- Type *LType = LHSI->getOperand(0)->getType();
- Type *RType = RHSC->getType();
- Type *LEleType = LType->getScalarType();
- Type *REleType = RType->getScalarType();
+ auto ConvertFltSema = [](const APFloat &Src, const fltSemantics &Sema) {
+ bool LosesInfo;
+ APFloat Dest = Src;
+ Dest.convert(Sema, APFloat::rmNearestTiesToEven, &LosesInfo);
+ return Dest;
+ };
- APFloat NextRValue = *RValue;
- NextRValue.next(RoundDown);
+ auto NextValue = [](const APFloat &Value, bool RoundDown) {
+ APFloat NextValue = Value;
+ NextValue.next(RoundDown);
+ return NextValue;
+ };
- // Promote 'RValue' and 'NextRValue' to 'LType'.
- APFloat ExtRValue = *RValue;
- APFloat ExtNextRValue = NextRValue;
- bool lossInfo;
- ExtRValue.convert(LEleType->getFltSemantics(), APFloat::rmNearestTiesToEven,
- &lossInfo);
- ExtNextRValue.convert(LEleType->getFltSemantics(),
- APFloat::rmNearestTiesToEven, &lossInfo);
+ APFloat NextCValue = NextValue(*CValue, RoundDown);
- // The (negative) maximum of 'RValue' may become infinity when rounded up
- // (down). Set the limit of 'ExtNextRValue'.
- if (NextRValue.isInfinity())
- ExtNextRValue = scalbn(ExtRValue, 1, APFloat::rmNearestTiesToEven);
+ Type *DestType = FPTrunc.getOperand(0)->getType();
+ const fltSemantics &DestFltSema =
+ DestType->getScalarType()->getFltSemantics();
- // Binary search to find the maximal (or minimal) value after 'RValue'
- // promotion. 'RValue' should obey normal comparison rules, which means nan or
- // inf is not allowed here.
- APFloat RoundValue{LEleType->getFltSemantics()};
+ APFloat ExtCValue = ConvertFltSema(*CValue, DestFltSema);
+ APFloat ExtNextCValue = ConvertFltSema(NextCValue, DestFltSema);
- APFloat LowBound = RoundDown ? ExtNextRValue : ExtRValue;
- APFloat UpBound = RoundDown ? ExtRValue : ExtNextRValue;
+ // When 'NextCValue' is infinity, use an imaged 'NextCValue' that equals
+ // 'CValue + bias' to avoid the infinity after conversion. The bias is
+ // estimated as 'CValue - PrevCValue', where 'PrevCValue' is the previous
+ // value of 'CValue'.
+ if (NextCValue.isInfinity()) {
+ APFloat PrevCValue = NextValue(*CValue, !RoundDown);
+ APFloat Bias = ConvertFltSema(*CValue - PrevCValue, DestFltSema);
- auto IsRoundingFound = [](const APFloat &LowBound, const APFloat &UpBound) {
- APFloat UpBoundNext = UpBound;
- UpBoundNext.next(true);
- return LowBound == UpBoundNext;
- };
+ ExtNextCValue = ExtCValue + Bias;
+ }
- auto EqualRValueAfterTrunc = [&](const APFloat &ExtValue) {
- APFloat TruncValue = ExtValue;
- TruncValue.convert(REleType->getFltSemantics(),
- APFloat::rmNearestTiesToEven, &lossInfo);
- return TruncValue == *RValue;
- };
+ APFloat ExtMidValue =
+ scalbn(ExtCValue + ExtNextCValue, -1, APFloat::rmNearestTiesToEven);
- while (true) {
- // Finish searching when 'LowBound' is next to 'UpBound'.
- if (IsRoundingFound(LowBound, UpBound)) {
- RoundValue = RoundDown ? UpBound : LowBound;
- break;
- }
+ const fltSemantics &SrcFltSema =
+ C.getType()->getScalarType()->getFltSemantics();
- APFloat Mid = scalbn(LowBound + UpBound, -1, APFloat::rmNearestTiesToEven);
- bool EqualRValue = EqualRValueAfterTrunc(Mid);
+ // 'MidValue' might be rounded to 'NextCValue'. Correct it here.
+ APFloat MidValue = ConvertFltSema(ExtMidValue, SrcFltSema);
+ if (MidValue != *CValue)
+ ExtMidValue.next(!RoundDown);
- // 'EqualRValue' indicates whether Mid is qualified to be the final round
- // value. if 'EqualRValue' == true, 'Mid' might be the final round value
- // if 'RoundDown' == true, 'UpBound' can't be the final round value
- // if 'RoudnDown' == false, 'DownBound' can't be the final round value
- // if 'EqualRValue' == false, 'Mid' can't be the final round value
- // if 'RoundDown' == true, 'DownBound' can't be the final round value
- // if 'RoundDown' == false, 'UpBound' can't be the final round value
- if (EqualRValue == RoundDown) {
- UpBound = Mid;
- } else {
- LowBound = Mid;
- }
+ // Check whether 'ExtMidValue' is a valid result since the assumption on
+ // imaged 'NextCValue' might not hold for new float types.
+ // ppc_fp128 can't pass here when converting from max float because of
+ // APFloat implementation.
+ if (NextCValue.isInfinity()) {
+ // ExtMidValue --- narrowed ---> Finite
+ if (ConvertFltSema(ExtMidValue, SrcFltSema).isInfinity())
+ return nullptr;
+
+ // NextExtMidValue --- narrowed ---> Infinity
+ APFloat NextExtMidValue = NextValue(ExtMidValue, RoundDown);
+ if (ConvertFltSema(NextExtMidValue, SrcFltSema).isFinite())
+ return nullptr;
}
- return new FCmpInst(Pred, LHSI->getOperand(0),
- ConstantFP::get(LType, RoundValue), "", &I);
+ return new FCmpInst(Pred, FPTrunc.getOperand(0),
+ ConstantFP::get(DestType, ExtMidValue), "", &I);
}
/// Optimize fabs(X) compared with zero.
@@ -8618,7 +8618,7 @@ Instruction *InstCombinerImpl::visitFCmpInst(FCmpInst &I) {
return Res;
break;
case Instruction::FPTrunc:
- if (Instruction *NV = foldFCmpFpTrunc(I, LHSI, RHSC))
+ if (Instruction *NV = foldFCmpFpTrunc(I, *LHSI, *RHSC))
return NV;
break;
}
diff --git a/llvm/test/Transforms/InstCombine/fold-fcmp-trunc-tmp.ll b/llvm/test/Transforms/InstCombine/fold-fcmp-trunc.ll
similarity index 87%
rename from llvm/test/Transforms/InstCombine/fold-fcmp-trunc-tmp.ll
rename to llvm/test/Transforms/InstCombine/fold-fcmp-trunc.ll
index 1d3dab8728a49..371f9b6807fe4 100644
--- a/llvm/test/Transforms/InstCombine/fold-fcmp-trunc-tmp.ll
+++ b/llvm/test/Transforms/InstCombine/fold-fcmp-trunc.ll
@@ -159,7 +159,7 @@ define i1 @fcmp_trunc_x86_fp80(x86_fp80 %0) {
define i1 @fcmp_trunc_ppc_fp128(ppc_fp128 %0) {
; CHECK-LABEL: define i1 @fcmp_trunc_ppc_fp128(
; CHECK-SAME: ppc_fp128 [[TMP0:%.*]]) {
-; CHECK-NEXT: [[RESULT:%.*]] = fcmp fast oge ppc_fp128 [[TMP0]], 0xM4058FFFFF0000000BD00000000000000
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp fast oge ppc_fp128 [[TMP0]], 0xM4058FFFFF00000000000000000000000
; CHECK-NEXT: ret i1 [[RESULT]]
;
%trunc = fptrunc ppc_fp128 %0 to float
@@ -288,7 +288,7 @@ define i1 @fcmp_trunc_mx(double %0) {
ret i1 %result
}
-; min representable
+; negative max representable
define i1 @fcmp_trunc_mn(double %0) {
; CHECK-LABEL: define i1 @fcmp_trunc_mn(
; CHECK-SAME: double [[TMP0:%.*]]) {
@@ -594,3 +594,81 @@ define i1 @fcmp_trunc_neg_fast_ult(double %0) {
}
+; max representable float to fp128
+define i1 @fcmp_trunc_mx_fp128(fp128 %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_mx_fp128(
+; CHECK-SAME: fp128 [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp ole fp128 [[TMP0]], 0xLFFFFFFFFFFFFFFFF407EFFFFFEFFFFFF
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc fp128 %0 to float
+ %result = fcmp ole float %trunc, 0x47EFFFFFE0000000
+ ret i1 %result
+}
+
+
+; max representable float to x86_fp80
+define i1 @fcmp_trunc_mx_x86_fp80(x86_fp80 %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_mx_x86_fp80(
+; CHECK-SAME: x86_fp80 [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp ule x86_fp80 [[TMP0]], 0xK407EFFFFFF7FFFFFFFFF
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc x86_fp80 %0 to float
+ %result = fcmp ule float %trunc, 0x47EFFFFFE0000000
+ ret i1 %result
+}
+
+
+; max representable float to ppc_fp128
+define i1 @fcmp_trunc_mx_ppc_fp128(ppc_fp128 %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_mx_ppc_fp128(
+; CHECK-SAME: ppc_fp128 [[TMP0:%.*]]) {
+; CHECK-NEXT: [[TRUNC:%.*]] = fptrunc ppc_fp128 [[TMP0]] to float
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp ole float [[TRUNC]], 0x47EFFFFFE0000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc ppc_fp128 %0 to float
+ %result = fcmp ole float %trunc, 0x47EFFFFFE0000000
+ ret i1 %result
+}
+
+
+; negative max representable float to fp128
+define i1 @fcmp_trunc_mn_fp128(fp128 %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_mn_fp128(
+; CHECK-SAME: fp128 [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp olt fp128 [[TMP0]], 0xL0000000000000000C07EFFFFF1000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc fp128 %0 to float
+ %result = fcmp olt float %trunc, 0xC7EFFFFF00000000
+ ret i1 %result
+}
+
+
+; negative max representable float to x86_fp80
+define i1 @fcmp_trunc_mn_x86_fp80(x86_fp80 %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_mn_x86_fp80(
+; CHECK-SAME: x86_fp80 [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp oge x86_fp80 [[TMP0]], 0xKC07EFFFFF88000000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc x86_fp80 %0 to float
+ %result = fcmp oge float %trunc, 0xC7EFFFFF00000000
+ ret i1 %result
+}
+
+
+; negative max representable float to ppc_fp128
+define i1 @fcmp_trunc_mn_ppc_fp128(ppc_fp128 %0) {
+; CHECK-LABEL: define i1 @fcmp_trunc_mn_ppc_fp128(
+; CHECK-SAME: ppc_fp128 [[TMP0:%.*]]) {
+; CHECK-NEXT: [[RESULT:%.*]] = fcmp uge ppc_fp128 [[TMP0]], 0xMC7EFFFFF100000000000000000000000
+; CHECK-NEXT: ret i1 [[RESULT]]
+;
+ %trunc = fptrunc ppc_fp128 %0 to float
+ %result = fcmp uge float %trunc, 0xC7EFFFFF00000000
+ ret i1 %result
+}
+
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