[llvm] [InstCombine] Handle isnormal idiom (PR #125454)
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Sun Feb 2 20:24:39 PST 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms
Author: Yingwei Zheng (dtcxzyw)
<details>
<summary>Changes</summary>
This patch improves the codegen of Rust's `is_normal` implementation: https://godbolt.org/z/1MPzcrrYG
Alive2: https://alive2.llvm.org/ce/z/hF9RWQ
---
Full diff: https://github.com/llvm/llvm-project/pull/125454.diff
2 Files Affected:
- (modified) llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp (+16)
- (modified) llvm/test/Transforms/InstCombine/fpclass-check-idioms.ll (+156)
``````````diff
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index ca8a20b4b7312d..55b6d4880814fe 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -3500,6 +3500,22 @@ Value *InstCombinerImpl::foldAndOrOfICmps(ICmpInst *LHS, ICmpInst *RHS,
}
}
+ // (X & ExpMask) != 0 && (X & ExpMask) != ExpMask -> isnormal(X)
+ // (X & ExpMask) == 0 || (X & ExpMask) == ExpMask -> !isnormal(X)
+ Value *X;
+ const APInt *MaskC;
+ if (LHS0 == RHS0 && PredL == PredR &&
+ PredL == (IsAnd ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ) &&
+ !I.getFunction()->hasFnAttribute(Attribute::NoImplicitFloat) &&
+ match(LHS0, m_And(m_ElementWiseBitCast(m_Value(X)), m_APInt(MaskC))) &&
+ X->getType()->getScalarType()->isIEEELikeFPTy() &&
+ APFloat(X->getType()->getScalarType()->getFltSemantics(), *MaskC)
+ .isPosInfinity() &&
+ ((LHSC->isZero() && *RHSC == *MaskC) ||
+ (RHSC->isZero() && *LHSC == *MaskC)))
+ return Builder.createIsFPClass(X, IsAnd ? FPClassTest::fcNormal
+ : ~FPClassTest::fcNormal);
+
return foldAndOrOfICmpsUsingRanges(LHS, RHS, IsAnd);
}
diff --git a/llvm/test/Transforms/InstCombine/fpclass-check-idioms.ll b/llvm/test/Transforms/InstCombine/fpclass-check-idioms.ll
index 66970a9d48ddf1..1d7e2bd96d1897 100644
--- a/llvm/test/Transforms/InstCombine/fpclass-check-idioms.ll
+++ b/llvm/test/Transforms/InstCombine/fpclass-check-idioms.ll
@@ -877,6 +877,162 @@ define i1 @isnan_idiom_ppc_fp128(ppc_fp128 %x) {
ret i1 %ret
}
+define i1 @fpclass_test_normal(float %num) {
+; CHECK-LABEL: define i1 @fpclass_test_normal(
+; CHECK-SAME: float [[NUM:%.*]]) {
+; CHECK-NEXT: [[RES:%.*]] = call i1 @llvm.is.fpclass.f32(float [[NUM]], i32 264)
+; CHECK-NEXT: ret i1 [[RES]]
+;
+ %cast = bitcast float %num to i32
+ %masked = and i32 %cast, 2139095040
+ %test1 = icmp ne i32 %masked, 2139095040
+ %test2 = icmp ne i32 %masked, 0
+ %res = and i1 %test1, %test2
+ ret i1 %res
+}
+
+define i1 @fpclass_test_normal_half(half %num) {
+; CHECK-LABEL: define i1 @fpclass_test_normal_half(
+; CHECK-SAME: half [[NUM:%.*]]) {
+; CHECK-NEXT: [[RES:%.*]] = call i1 @llvm.is.fpclass.f16(half [[NUM]], i32 264)
+; CHECK-NEXT: ret i1 [[RES]]
+;
+ %cast = bitcast half %num to i16
+ %masked = and i16 %cast, 31744
+ %test1 = icmp ne i16 %masked, 31744
+ %test2 = icmp ne i16 %masked, 0
+ %res = and i1 %test1, %test2
+ ret i1 %res
+}
+
+define <2 x i1> @fpclass_test_normal_half_vec(<2 x half> %num) {
+; CHECK-LABEL: define <2 x i1> @fpclass_test_normal_half_vec(
+; CHECK-SAME: <2 x half> [[NUM:%.*]]) {
+; CHECK-NEXT: [[RES:%.*]] = call <2 x i1> @llvm.is.fpclass.v2f16(<2 x half> [[NUM]], i32 264)
+; CHECK-NEXT: ret <2 x i1> [[RES]]
+;
+ %cast = bitcast <2 x half> %num to <2 x i16>
+ %masked = and <2 x i16> %cast, splat(i16 31744)
+ %test1 = icmp ne <2 x i16> %masked, splat(i16 31744)
+ %test2 = icmp ne <2 x i16> %masked, zeroinitializer
+ %res = and <2 x i1> %test1, %test2
+ ret <2 x i1> %res
+}
+
+define i1 @fpclass_test_not_normal(float %num) {
+; CHECK-LABEL: define i1 @fpclass_test_not_normal(
+; CHECK-SAME: float [[NUM:%.*]]) {
+; CHECK-NEXT: [[RES:%.*]] = call i1 @llvm.is.fpclass.f32(float [[NUM]], i32 759)
+; CHECK-NEXT: ret i1 [[RES]]
+;
+ %cast = bitcast float %num to i32
+ %masked = and i32 %cast, 2139095040
+ %test1 = icmp eq i32 %masked, 2139095040
+ %test2 = icmp eq i32 %masked, 0
+ %res = or i1 %test1, %test2
+ ret i1 %res
+}
+
+define i1 @fpclass_test_normal_commuted(float %num) {
+; CHECK-LABEL: define i1 @fpclass_test_normal_commuted(
+; CHECK-SAME: float [[NUM:%.*]]) {
+; CHECK-NEXT: [[RES:%.*]] = call i1 @llvm.is.fpclass.f32(float [[NUM]], i32 264)
+; CHECK-NEXT: ret i1 [[RES]]
+;
+ %cast = bitcast float %num to i32
+ %masked = and i32 %cast, 2139095040
+ %test1 = icmp ne i32 %masked, 2139095040
+ %test2 = icmp ne i32 %masked, 0
+ %res = and i1 %test2, %test1
+ ret i1 %res
+}
+
+define i1 @fpclass_test_normal_mismatch_pred(float %num) {
+; CHECK-LABEL: define i1 @fpclass_test_normal_mismatch_pred(
+; CHECK-SAME: float [[NUM:%.*]]) {
+; CHECK-NEXT: [[CAST:%.*]] = bitcast float [[NUM]] to i32
+; CHECK-NEXT: [[MASKED:%.*]] = and i32 [[CAST]], 2139095040
+; CHECK-NEXT: [[TEST2:%.*]] = icmp eq i32 [[MASKED]], 0
+; CHECK-NEXT: ret i1 [[TEST2]]
+;
+ %cast = bitcast float %num to i32
+ %masked = and i32 %cast, 2139095040
+ %test1 = icmp ne i32 %masked, 2139095040
+ %test2 = icmp eq i32 %masked, 0
+ %res = and i1 %test1, %test2
+ ret i1 %res
+}
+
+define i1 @fpclass_test_normal_no_implicit_fp(float %num) #0 {
+; CHECK-LABEL: define i1 @fpclass_test_normal_no_implicit_fp(
+; CHECK-SAME: float [[NUM:%.*]]) #[[ATTR1]] {
+; CHECK-NEXT: [[CAST:%.*]] = bitcast float [[NUM]] to i32
+; CHECK-NEXT: [[MASKED:%.*]] = and i32 [[CAST]], 2139095040
+; CHECK-NEXT: [[TEST1:%.*]] = icmp ne i32 [[MASKED]], 2139095040
+; CHECK-NEXT: [[TEST2:%.*]] = icmp ne i32 [[MASKED]], 0
+; CHECK-NEXT: [[RES:%.*]] = and i1 [[TEST1]], [[TEST2]]
+; CHECK-NEXT: ret i1 [[RES]]
+;
+ %cast = bitcast float %num to i32
+ %masked = and i32 %cast, 2139095040
+ %test1 = icmp ne i32 %masked, 2139095040
+ %test2 = icmp ne i32 %masked, 0
+ %res = and i1 %test1, %test2
+ ret i1 %res
+}
+
+define i1 @fpclass_test_normal_invalid_constant1(float %num) {
+; CHECK-LABEL: define i1 @fpclass_test_normal_invalid_constant1(
+; CHECK-SAME: float [[NUM:%.*]]) {
+; CHECK-NEXT: [[CAST:%.*]] = bitcast float [[NUM]] to i32
+; CHECK-NEXT: [[MASKED:%.*]] = and i32 [[CAST]], 2139095039
+; CHECK-NEXT: [[TEST1:%.*]] = icmp ne i32 [[MASKED]], 2139095039
+; CHECK-NEXT: [[TEST2:%.*]] = icmp ne i32 [[MASKED]], 0
+; CHECK-NEXT: [[RES:%.*]] = and i1 [[TEST1]], [[TEST2]]
+; CHECK-NEXT: ret i1 [[RES]]
+;
+ %cast = bitcast float %num to i32
+ %masked = and i32 %cast, 2139095039
+ %test1 = icmp ne i32 %masked, 2139095039
+ %test2 = icmp ne i32 %masked, 0
+ %res = and i1 %test1, %test2
+ ret i1 %res
+}
+
+define i1 @fpclass_test_normal_invalid_constant2(float %num) {
+; CHECK-LABEL: define i1 @fpclass_test_normal_invalid_constant2(
+; CHECK-SAME: float [[NUM:%.*]]) {
+; CHECK-NEXT: [[CAST:%.*]] = bitcast float [[NUM]] to i32
+; CHECK-NEXT: [[MASKED:%.*]] = and i32 [[CAST]], 2139095040
+; CHECK-NEXT: [[TEST1:%.*]] = icmp ne i32 [[MASKED]], 2130706432
+; CHECK-NEXT: [[TEST2:%.*]] = icmp ne i32 [[MASKED]], 0
+; CHECK-NEXT: [[RES:%.*]] = and i1 [[TEST1]], [[TEST2]]
+; CHECK-NEXT: ret i1 [[RES]]
+;
+ %cast = bitcast float %num to i32
+ %masked = and i32 %cast, 2139095040
+ %test1 = icmp ne i32 %masked, 2130706432
+ %test2 = icmp ne i32 %masked, 0
+ %res = and i1 %test1, %test2
+ ret i1 %res
+}
+
+define i1 @fpclass_test_normal_invalid_constant3(float %num) {
+; CHECK-LABEL: define i1 @fpclass_test_normal_invalid_constant3(
+; CHECK-SAME: float [[NUM:%.*]]) {
+; CHECK-NEXT: [[CAST:%.*]] = bitcast float [[NUM]] to i32
+; CHECK-NEXT: [[TMP1:%.*]] = and i32 [[CAST]], 2130706432
+; CHECK-NEXT: [[RES:%.*]] = icmp ne i32 [[TMP1]], 2130706432
+; CHECK-NEXT: ret i1 [[RES]]
+;
+ %cast = bitcast float %num to i32
+ %masked = and i32 %cast, 2139095040
+ %test1 = icmp ne i32 %masked, 2139095040
+ %test2 = icmp ne i32 %masked, 2130706432
+ %res = and i1 %test1, %test2
+ ret i1 %res
+}
+
declare void @usei32(i32)
attributes #0 = { noimplicitfloat }
``````````
</details>
https://github.com/llvm/llvm-project/pull/125454
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