[llvm] 86f0399 - [InstCombine] Fold expression using basic properties of floor and ceiling function (#107107)

via llvm-commits llvm-commits at lists.llvm.org
Sun Sep 15 03:25:04 PDT 2024


Author: c8ef
Date: 2024-09-15T14:25:00+04:00
New Revision: 86f0399c1fdec80c34e22821607696a485857421

URL: https://github.com/llvm/llvm-project/commit/86f0399c1fdec80c34e22821607696a485857421
DIFF: https://github.com/llvm/llvm-project/commit/86f0399c1fdec80c34e22821607696a485857421.diff

LOG: [InstCombine] Fold expression using basic properties of floor and ceiling function (#107107)

alive2: ~~https://alive2.llvm.org/ce/z/Ag3Ki7~~
https://alive2.llvm.org/ce/z/ywP5t2
related: #76438

This patch adds the following foldings: `floor(x) <= x --> true` and `x
<= ceil(x) --> true`. We leverage the properties of these math functions
and ensure there is no floating point input of `nan`.

---------

Co-authored-by: Yingwei Zheng <dtcxzyw at qq.com>

Added: 
    llvm/test/Transforms/InstCombine/fp-floor-ceil.ll

Modified: 
    llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 8e8d472a5df1d3..5cdfeada7f0aa2 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -8178,6 +8178,75 @@ static Instruction *foldFCmpFSubIntoFCmp(FCmpInst &I, Instruction *LHSI,
   return nullptr;
 }
 
+static Instruction *foldFCmpWithFloorAndCeil(FCmpInst &I,
+                                             InstCombinerImpl &IC) {
+  Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
+  Type *OpType = LHS->getType();
+  CmpInst::Predicate Pred = I.getPredicate();
+
+  bool FloorX = match(LHS, m_Intrinsic<Intrinsic::floor>(m_Specific(RHS)));
+  bool CeilX = match(LHS, m_Intrinsic<Intrinsic::ceil>(m_Specific(RHS)));
+
+  if (!FloorX && !CeilX) {
+    if ((FloorX = match(RHS, m_Intrinsic<Intrinsic::floor>(m_Specific(LHS)))) ||
+        (CeilX = match(RHS, m_Intrinsic<Intrinsic::ceil>(m_Specific(LHS))))) {
+      std::swap(LHS, RHS);
+      Pred = I.getSwappedPredicate();
+    }
+  }
+
+  switch (Pred) {
+  case FCmpInst::FCMP_OLE:
+    // fcmp ole floor(x), x => fcmp ord x, 0
+    if (FloorX)
+      return new FCmpInst(FCmpInst::FCMP_ORD, RHS, ConstantFP::getZero(OpType),
+                          "", &I);
+    break;
+  case FCmpInst::FCMP_OGT:
+    // fcmp ogt floor(x), x => false
+    if (FloorX)
+      return IC.replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
+    break;
+  case FCmpInst::FCMP_OGE:
+    // fcmp oge ceil(x), x => fcmp ord x, 0
+    if (CeilX)
+      return new FCmpInst(FCmpInst::FCMP_ORD, RHS, ConstantFP::getZero(OpType),
+                          "", &I);
+    break;
+  case FCmpInst::FCMP_OLT:
+    // fcmp olt ceil(x), x => false
+    if (CeilX)
+      return IC.replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
+    break;
+  case FCmpInst::FCMP_ULE:
+    // fcmp ule floor(x), x => true
+    if (FloorX)
+      return IC.replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
+    break;
+  case FCmpInst::FCMP_UGT:
+    // fcmp ugt floor(x), x => fcmp uno x, 0
+    if (FloorX)
+      return new FCmpInst(FCmpInst::FCMP_UNO, RHS, ConstantFP::getZero(OpType),
+                          "", &I);
+    break;
+  case FCmpInst::FCMP_UGE:
+    // fcmp uge ceil(x), x => true
+    if (CeilX)
+      return IC.replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
+    break;
+  case FCmpInst::FCMP_ULT:
+    // fcmp ult ceil(x), x => fcmp uno x, 0
+    if (CeilX)
+      return new FCmpInst(FCmpInst::FCMP_UNO, RHS, ConstantFP::getZero(OpType),
+                          "", &I);
+    break;
+  default:
+    break;
+  }
+
+  return nullptr;
+}
+
 Instruction *InstCombinerImpl::visitFCmpInst(FCmpInst &I) {
   bool Changed = false;
 
@@ -8382,6 +8451,9 @@ Instruction *InstCombinerImpl::visitFCmpInst(FCmpInst &I) {
   if (Instruction *R = foldSqrtWithFcmpZero(I, *this))
     return R;
 
+  if (Instruction *R = foldFCmpWithFloorAndCeil(I, *this))
+    return R;
+
   if (match(Op0, m_FNeg(m_Value(X)))) {
     // fcmp pred (fneg X), C --> fcmp swap(pred) X, -C
     Constant *C;

diff  --git a/llvm/test/Transforms/InstCombine/fp-floor-ceil.ll b/llvm/test/Transforms/InstCombine/fp-floor-ceil.ll
new file mode 100644
index 00000000000000..c90b7ee11310cb
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/fp-floor-ceil.ll
@@ -0,0 +1,260 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+
+define i1 @floor_x_ole(float %x) {
+; CHECK-LABEL: @floor_x_ole(
+; CHECK-NEXT:    [[RET:%.*]] = fcmp ninf ord float [[X:%.*]], 0.000000e+00
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %floor = call float @llvm.floor.f32(float %x)
+  %ret = fcmp ninf ole float %floor, %x
+  ret i1 %ret
+}
+
+define i1 @floor_x_ule(float %x) {
+; CHECK-LABEL: @floor_x_ule(
+; CHECK-NEXT:    ret i1 true
+;
+  %floor = call float @llvm.floor.f32(float %x)
+  %ret = fcmp ule float %floor, %x
+  ret i1 %ret
+}
+
+define i1 @floor_x_ogt(float %x) {
+; CHECK-LABEL: @floor_x_ogt(
+; CHECK-NEXT:    ret i1 false
+;
+  %floor = call float @llvm.floor.f32(float %x)
+  %ret = fcmp ogt float %floor, %x
+  ret i1 %ret
+}
+
+define i1 @floor_x_ugt(float %x) {
+; CHECK-LABEL: @floor_x_ugt(
+; CHECK-NEXT:    [[RET:%.*]] = fcmp ninf uno float [[X:%.*]], 0.000000e+00
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %floor = call float @llvm.floor.f32(float %x)
+  %ret = fcmp ninf ugt float %floor, %x
+  ret i1 %ret
+}
+
+define i1 @x_floor_oge(float %x) {
+; CHECK-LABEL: @x_floor_oge(
+; CHECK-NEXT:    [[RET:%.*]] = fcmp ninf ord float [[X:%.*]], 0.000000e+00
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %floor = call float @llvm.floor.f32(float %x)
+  %ret = fcmp ninf oge float %x, %floor
+  ret i1 %ret
+}
+
+define i1 @x_floor_uge(float %x) {
+; CHECK-LABEL: @x_floor_uge(
+; CHECK-NEXT:    ret i1 true
+;
+  %floor = call float @llvm.floor.f32(float %x)
+  %ret = fcmp uge float %x, %floor
+  ret i1 %ret
+}
+
+define i1 @x_floor_olt(float %x) {
+; CHECK-LABEL: @x_floor_olt(
+; CHECK-NEXT:    ret i1 false
+;
+  %floor = call float @llvm.floor.f32(float %x)
+  %ret = fcmp olt float %x, %floor
+  ret i1 %ret
+}
+
+define i1 @x_floor_ult(float %x) {
+; CHECK-LABEL: @x_floor_ult(
+; CHECK-NEXT:    [[RET:%.*]] = fcmp ninf uno float [[X:%.*]], 0.000000e+00
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %floor = call float @llvm.floor.f32(float %x)
+  %ret = fcmp ninf ult float %x, %floor
+  ret i1 %ret
+}
+
+define <2 x i1> @x_floor_olt_vec(<2 x float> %x) {
+; CHECK-LABEL: @x_floor_olt_vec(
+; CHECK-NEXT:    ret <2 x i1> zeroinitializer
+;
+  %floor = call <2 x float> @llvm.floor.f32(<2 x float> %x)
+  %ret = fcmp olt <2 x float> %x, %floor
+  ret <2 x i1> %ret
+}
+
+define i1 @x_floor_ole_neg(float %x) {
+; CHECK-LABEL: @x_floor_ole_neg(
+; CHECK-NEXT:    [[FLOOR:%.*]] = call float @llvm.floor.f32(float [[X:%.*]])
+; CHECK-NEXT:    [[RET:%.*]] = fcmp ole float [[X]], [[FLOOR]]
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %floor = call float @llvm.floor.f32(float %x)
+  %ret = fcmp ole float %x, %floor
+  ret i1 %ret
+}
+
+define i1 @x_floor_ogt_neg(float %x) {
+; CHECK-LABEL: @x_floor_ogt_neg(
+; CHECK-NEXT:    [[FLOOR:%.*]] = call float @llvm.floor.f32(float [[X:%.*]])
+; CHECK-NEXT:    [[RET:%.*]] = fcmp ogt float [[X]], [[FLOOR]]
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %floor = call float @llvm.floor.f32(float %x)
+  %ret = fcmp ogt float %x, %floor
+  ret i1 %ret
+}
+
+define i1 @x_floor_ueq_neg(float %x) {
+; CHECK-LABEL: @x_floor_ueq_neg(
+; CHECK-NEXT:    [[FLOOR:%.*]] = call float @llvm.floor.f32(float [[X:%.*]])
+; CHECK-NEXT:    [[RET:%.*]] = fcmp ueq float [[X]], [[FLOOR]]
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %floor = call float @llvm.floor.f32(float %x)
+  %ret = fcmp ueq float %x, %floor
+  ret i1 %ret
+}
+
+define i1 @x_floor_une_neg(float %x) {
+; CHECK-LABEL: @x_floor_une_neg(
+; CHECK-NEXT:    [[FLOOR:%.*]] = call float @llvm.floor.f32(float [[X:%.*]])
+; CHECK-NEXT:    [[RET:%.*]] = fcmp une float [[X]], [[FLOOR]]
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %floor = call float @llvm.floor.f32(float %x)
+  %ret = fcmp une float %x, %floor
+  ret i1 %ret
+}
+
+define i1 @ceil_x_oge(float %x) {
+; CHECK-LABEL: @ceil_x_oge(
+; CHECK-NEXT:    [[RET:%.*]] = fcmp ninf ord float [[X:%.*]], 0.000000e+00
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %ceil = call float @llvm.ceil.f32(float %x)
+  %ret = fcmp ninf oge float %ceil, %x
+  ret i1 %ret
+}
+
+define i1 @ceil_x_uge(float %x) {
+; CHECK-LABEL: @ceil_x_uge(
+; CHECK-NEXT:    ret i1 true
+;
+  %ceil = call float @llvm.ceil.f32(float %x)
+  %ret = fcmp uge float %ceil, %x
+  ret i1 %ret
+}
+
+define i1 @ceil_x_olt(float %x) {
+; CHECK-LABEL: @ceil_x_olt(
+; CHECK-NEXT:    ret i1 false
+;
+  %ceil = call float @llvm.ceil.f32(float %x)
+  %ret = fcmp olt float %ceil, %x
+  ret i1 %ret
+}
+
+define i1 @ceil_x_ult(float %x) {
+; CHECK-LABEL: @ceil_x_ult(
+; CHECK-NEXT:    [[RET:%.*]] = fcmp ninf uno float [[X:%.*]], 0.000000e+00
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %ceil = call float @llvm.ceil.f32(float %x)
+  %ret = fcmp ninf ult float %ceil, %x
+  ret i1 %ret
+}
+
+define i1 @x_ceil_ole(float %x) {
+; CHECK-LABEL: @x_ceil_ole(
+; CHECK-NEXT:    [[RET:%.*]] = fcmp ninf ord float [[X:%.*]], 0.000000e+00
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %ceil = call float @llvm.ceil.f32(float %x)
+  %ret = fcmp ninf ole float %x, %ceil
+  ret i1 %ret
+}
+
+define i1 @x_ceil_ule(float %x) {
+; CHECK-LABEL: @x_ceil_ule(
+; CHECK-NEXT:    ret i1 true
+;
+  %ceil = call float @llvm.ceil.f32(float %x)
+  %ret = fcmp ule float %x, %ceil
+  ret i1 %ret
+}
+
+define i1 @x_ceil_ogt(float %x) {
+; CHECK-LABEL: @x_ceil_ogt(
+; CHECK-NEXT:    ret i1 false
+;
+  %ceil = call float @llvm.ceil.f32(float %x)
+  %ret = fcmp ogt float %x, %ceil
+  ret i1 %ret
+}
+
+define i1 @x_ceil_ugt(float %x) {
+; CHECK-LABEL: @x_ceil_ugt(
+; CHECK-NEXT:    [[RET:%.*]] = fcmp ninf uno float [[X:%.*]], 0.000000e+00
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %ceil = call float @llvm.ceil.f32(float %x)
+  %ret = fcmp ninf ugt float %x, %ceil
+  ret i1 %ret
+}
+
+define <2 x i1> @x_ceil_ogt_vec(<2 x float> %x) {
+; CHECK-LABEL: @x_ceil_ogt_vec(
+; CHECK-NEXT:    ret <2 x i1> zeroinitializer
+;
+  %ceil = call <2 x float> @llvm.ceil.f32(<2 x float> %x)
+  %ret = fcmp ogt <2 x float> %x, %ceil
+  ret <2 x i1> %ret
+}
+
+define i1 @x_ceil_oge_neg(float %x) {
+; CHECK-LABEL: @x_ceil_oge_neg(
+; CHECK-NEXT:    [[CEIL:%.*]] = call float @llvm.ceil.f32(float [[X:%.*]])
+; CHECK-NEXT:    [[RET:%.*]] = fcmp oge float [[X]], [[CEIL]]
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %ceil = call float @llvm.ceil.f32(float %x)
+  %ret = fcmp oge float %x, %ceil
+  ret i1 %ret
+}
+
+define i1 @x_ceil_olt_neg(float %x) {
+; CHECK-LABEL: @x_ceil_olt_neg(
+; CHECK-NEXT:    [[CEIL:%.*]] = call float @llvm.ceil.f32(float [[X:%.*]])
+; CHECK-NEXT:    [[RET:%.*]] = fcmp olt float [[X]], [[CEIL]]
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %ceil = call float @llvm.ceil.f32(float %x)
+  %ret = fcmp olt float %x, %ceil
+  ret i1 %ret
+}
+
+define i1 @x_ceil_oeq_neg(float %x) {
+; CHECK-LABEL: @x_ceil_oeq_neg(
+; CHECK-NEXT:    [[CEIL:%.*]] = call float @llvm.ceil.f32(float [[X:%.*]])
+; CHECK-NEXT:    [[RET:%.*]] = fcmp oeq float [[X]], [[CEIL]]
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %ceil = call float @llvm.ceil.f32(float %x)
+  %ret = fcmp oeq float %x, %ceil
+  ret i1 %ret
+}
+
+define i1 @x_ceil_one_neg(float %x) {
+; CHECK-LABEL: @x_ceil_one_neg(
+; CHECK-NEXT:    [[CEIL:%.*]] = call float @llvm.ceil.f32(float [[X:%.*]])
+; CHECK-NEXT:    [[RET:%.*]] = fcmp one float [[X]], [[CEIL]]
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %ceil = call float @llvm.ceil.f32(float %x)
+  %ret = fcmp one float %x, %ceil
+  ret i1 %ret
+}


        


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