[llvm] [InstCombine] Handle isNanOrInf idioms (PR #80414)
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Fri Feb 2 03:11:45 PST 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms
Author: Yingwei Zheng (dtcxzyw)
<details>
<summary>Changes</summary>
This patch folds:
```
(icmp eq (and (bitcast X to int), ExponentMask), ExponentMask) --> llvm.is.fpclass(X, fcInf|fcNan)
(icmp ne (and (bitcast X to int), ExponentMask), ExponentMask) --> llvm.is.fpclass(X, ~(fcInf|fcNan))
```
Alive2: https://alive2.llvm.org/ce/z/_hXAAF
---
Full diff: https://github.com/llvm/llvm-project/pull/80414.diff
2 Files Affected:
- (modified) llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp (+29)
- (added) llvm/test/Transforms/InstCombine/fpclass-check-idioms.ll (+177)
``````````diff
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index d295853798b80..0fe75309296b4 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -1827,6 +1827,35 @@ Instruction *InstCombinerImpl::foldICmpAndConstConst(ICmpInst &Cmp,
}
}
+ // (icmp eq (and (bitcast X to int), ExponentMask), ExponentMask) -->
+ // llvm.is.fpclass(X, fcInf|fcNan)
+ // (icmp ne (and (bitcast X to int), ExponentMask), ExponentMask) -->
+ // llvm.is.fpclass(X, ~(fcInf|fcNan))
+ Value *V;
+ if (!Cmp.getParent()->getParent()->hasFnAttribute(
+ Attribute::NoImplicitFloat) &&
+ Cmp.isEquality() && match(X, m_OneUse(m_BitCast(m_Value(V))))) {
+ Type *SrcType = V->getType();
+ Type *DstType = X->getType();
+ // Make sure the bitcast doesn't change between scalar and vector and
+ // doesn't change the number of vector elements.
+ if (SrcType->isVectorTy() == DstType->isVectorTy() &&
+ SrcType->getScalarSizeInBits() == DstType->getScalarSizeInBits()) {
+ Type *FPType = SrcType->getScalarType();
+ if (FPType->isIEEELikeFPTy() && C1 == *C2) {
+ APInt ExponentMask = APInt::getBitsSet(
+ FPType->getScalarSizeInBits(), FPType->getFPMantissaWidth() - 1,
+ FPType->getScalarSizeInBits() - 1);
+ if (C1 == ExponentMask) {
+ unsigned Mask = FPClassTest::fcNan | FPClassTest::fcInf;
+ if (isICMP_NE)
+ Mask = ~Mask & fcAllFlags;
+ return replaceInstUsesWith(Cmp, Builder.createIsFPClass(V, Mask));
+ }
+ }
+ }
+ }
+
return nullptr;
}
diff --git a/llvm/test/Transforms/InstCombine/fpclass-check-idioms.ll b/llvm/test/Transforms/InstCombine/fpclass-check-idioms.ll
new file mode 100644
index 0000000000000..dd4a3e0afb50a
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/fpclass-check-idioms.ll
@@ -0,0 +1,177 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
+; RUN: opt -S -passes=instcombine < %s | FileCheck %s
+
+define i1 @f32_fcnan_fcinf(float %a) {
+; CHECK-LABEL: define i1 @f32_fcnan_fcinf(
+; CHECK-SAME: float [[A:%.*]]) {
+; CHECK-NEXT: [[TMP1:%.*]] = call float @llvm.fabs.f32(float [[A]])
+; CHECK-NEXT: [[CMP:%.*]] = fcmp ueq float [[TMP1]], 0x7FF0000000000000
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %i32 = bitcast float %a to i32
+ %and = and i32 %i32, 2139095040
+ %cmp = icmp eq i32 %and, 2139095040
+ ret i1 %cmp
+}
+
+define i1 @f32_not_fcnan_fcinf(float %a) {
+; CHECK-LABEL: define i1 @f32_not_fcnan_fcinf(
+; CHECK-SAME: float [[A:%.*]]) {
+; CHECK-NEXT: [[TMP1:%.*]] = call float @llvm.fabs.f32(float [[A]])
+; CHECK-NEXT: [[CMP:%.*]] = fcmp one float [[TMP1]], 0x7FF0000000000000
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %i32 = bitcast float %a to i32
+ %and = and i32 %i32, 2139095040
+ %cmp = icmp ne i32 %and, 2139095040
+ ret i1 %cmp
+}
+
+define i1 @f64_fcnan_fcinf(double %a) {
+; CHECK-LABEL: define i1 @f64_fcnan_fcinf(
+; CHECK-SAME: double [[A:%.*]]) {
+; CHECK-NEXT: [[TMP1:%.*]] = call double @llvm.fabs.f64(double [[A]])
+; CHECK-NEXT: [[CMP:%.*]] = fcmp ueq double [[TMP1]], 0x7FF0000000000000
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %i64 = bitcast double %a to i64
+ %and = and i64 %i64, 9218868437227405312
+ %cmp = icmp eq i64 %and, 9218868437227405312
+ ret i1 %cmp
+}
+
+; TODO: handle more fpclass check idioms
+define i1 @f32_fcinf(float %a) {
+; CHECK-LABEL: define i1 @f32_fcinf(
+; CHECK-SAME: float [[A:%.*]]) {
+; CHECK-NEXT: [[TMP1:%.*]] = call float @llvm.fabs.f32(float [[A]])
+; CHECK-NEXT: [[AND:%.*]] = bitcast float [[TMP1]] to i32
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[AND]], 2139095040
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %i32 = bitcast float %a to i32
+ %and = and i32 %i32, 2147483647
+ %cmp = icmp eq i32 %and, 2139095040
+ ret i1 %cmp
+}
+
+define i1 @f32_fcnan(float %a) {
+; CHECK-LABEL: define i1 @f32_fcnan(
+; CHECK-SAME: float [[A:%.*]]) {
+; CHECK-NEXT: [[I32:%.*]] = bitcast float [[A]] to i32
+; CHECK-NEXT: [[AND1:%.*]] = and i32 [[I32]], 2139095040
+; CHECK-NEXT: [[CMP1:%.*]] = icmp eq i32 [[AND1]], 2139095040
+; CHECK-NEXT: [[AND2:%.*]] = and i32 [[I32]], 8388607
+; CHECK-NEXT: [[CMP2:%.*]] = icmp ne i32 [[AND2]], 0
+; CHECK-NEXT: [[RES:%.*]] = and i1 [[CMP1]], [[CMP2]]
+; CHECK-NEXT: ret i1 [[RES]]
+;
+ %i32 = bitcast float %a to i32
+ %and1 = and i32 %i32, 2139095040
+ %cmp1 = icmp eq i32 %and1, 2139095040
+ %and2 = and i32 %i32, 8388607
+ %cmp2 = icmp ne i32 %and2, 0
+ %res = and i1 %cmp1, %cmp2
+ ret i1 %res
+}
+
+; Negative tests
+
+define i1 @f32_fcnan_fcinf_wrong_mask1(float %a) {
+; CHECK-LABEL: define i1 @f32_fcnan_fcinf_wrong_mask1(
+; CHECK-SAME: float [[A:%.*]]) {
+; CHECK-NEXT: [[I32:%.*]] = bitcast float [[A]] to i32
+; CHECK-NEXT: [[AND:%.*]] = and i32 [[I32]], 2139095041
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[AND]], 2139095040
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %i32 = bitcast float %a to i32
+ %and = and i32 %i32, 2139095041
+ %cmp = icmp eq i32 %and, 2139095040
+ ret i1 %cmp
+}
+
+define i1 @f32_fcnan_fcinf_wrong_mask2(float %a) {
+; CHECK-LABEL: define i1 @f32_fcnan_fcinf_wrong_mask2(
+; CHECK-SAME: float [[A:%.*]]) {
+; CHECK-NEXT: [[I32:%.*]] = bitcast float [[A]] to i32
+; CHECK-NEXT: [[AND:%.*]] = and i32 [[I32]], 2139095040
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[AND]], 2130706432
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %i32 = bitcast float %a to i32
+ %and = and i32 %i32, 2139095040
+ %cmp = icmp eq i32 %and, 2130706432
+ ret i1 %cmp
+}
+
+define i1 @f64_fcnan_fcinf_wrong_mask3(double %a) {
+; CHECK-LABEL: define i1 @f64_fcnan_fcinf_wrong_mask3(
+; CHECK-SAME: double [[A:%.*]]) {
+; CHECK-NEXT: [[I64:%.*]] = bitcast double [[A]] to i64
+; CHECK-NEXT: [[AND:%.*]] = and i64 [[I64]], 2139095040
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i64 [[AND]], 2139095040
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %i64 = bitcast double %a to i64
+ %and = and i64 %i64, 2139095040
+ %cmp = icmp eq i64 %and, 2139095040
+ ret i1 %cmp
+}
+
+define i1 @f32_fcnan_fcinf_wrong_pred(float %a) {
+; CHECK-LABEL: define i1 @f32_fcnan_fcinf_wrong_pred(
+; CHECK-SAME: float [[A:%.*]]) {
+; CHECK-NEXT: [[TMP1:%.*]] = call float @llvm.fabs.f32(float [[A]])
+; CHECK-NEXT: [[CMP:%.*]] = fcmp one float [[TMP1]], 0x7FF0000000000000
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %i32 = bitcast float %a to i32
+ %and = and i32 %i32, 2139095040
+ %cmp = icmp slt i32 %and, 2139095040
+ ret i1 %cmp
+}
+
+define i1 @f32_fcnan_fcinf_wrong_type1(<2 x float> %a) {
+; CHECK-LABEL: define i1 @f32_fcnan_fcinf_wrong_type1(
+; CHECK-SAME: <2 x float> [[A:%.*]]) {
+; CHECK-NEXT: [[I64:%.*]] = bitcast <2 x float> [[A]] to i64
+; CHECK-NEXT: [[AND:%.*]] = and i64 [[I64]], 2139095040
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i64 [[AND]], 2139095040
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %i64 = bitcast <2 x float> %a to i64
+ %and = and i64 %i64, 2139095040
+ %cmp = icmp eq i64 %and, 2139095040
+ ret i1 %cmp
+}
+
+define i1 @f32_fcnan_fcinf_wrong_type2(x86_fp80 %a) {
+; CHECK-LABEL: define i1 @f32_fcnan_fcinf_wrong_type2(
+; CHECK-SAME: x86_fp80 [[A:%.*]]) {
+; CHECK-NEXT: [[I80:%.*]] = bitcast x86_fp80 [[A]] to i80
+; CHECK-NEXT: [[AND:%.*]] = and i80 [[I80]], 2139095040
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i80 [[AND]], 2139095040
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %i80 = bitcast x86_fp80 %a to i80
+ %and = and i80 %i80, 2139095040
+ %cmp = icmp eq i80 %and, 2139095040
+ ret i1 %cmp
+}
+
+define i1 @f32_fcnan_fcinf_noimplicitfloat(float %a) #0 {
+; CHECK-LABEL: define i1 @f32_fcnan_fcinf_noimplicitfloat(
+; CHECK-SAME: float [[A:%.*]]) #[[ATTR0:[0-9]+]] {
+; CHECK-NEXT: [[I32:%.*]] = bitcast float [[A]] to i32
+; CHECK-NEXT: [[AND:%.*]] = and i32 [[I32]], 2139095040
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[AND]], 2139095040
+; CHECK-NEXT: ret i1 [[CMP]]
+;
+ %i32 = bitcast float %a to i32
+ %and = and i32 %i32, 2139095040
+ %cmp = icmp eq i32 %and, 2139095040
+ ret i1 %cmp
+}
+
+attributes #0 = { noimplicitfloat }
``````````
</details>
https://github.com/llvm/llvm-project/pull/80414
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