[llvm] [SimplifyLibCalls] Constant fold nan libcall (PR #101459)
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Thu Aug 1 00:21:59 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms
Author: Yingwei Zheng (dtcxzyw)
<details>
<summary>Changes</summary>
Reference: https://en.cppreference.com/w/c/numeric/math/nan
The logic is copied from clang frontend:
https://github.com/llvm/llvm-project/blob/1d2b2d29d733200b704f38d220d22ecc07d6cf42/clang/lib/AST/ExprConstant.cpp#L14741-L14777
---
Full diff: https://github.com/llvm/llvm-project/pull/101459.diff
5 Files Affected:
- (modified) llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp (+20)
- (added) llvm/test/Transforms/InstCombine/nan.ll (+41)
- (added) llvm/test/Transforms/InstCombine/nanl-fp128.ll (+32)
- (added) llvm/test/Transforms/InstCombine/nanl-fp80.ll (+32)
- (added) llvm/test/Transforms/InstCombine/nanl-ppc-fp128.ll (+32)
``````````diff
diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
index 4100471eaaa1d..948e510be5c32 100644
--- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -3858,6 +3858,22 @@ Value *LibCallSimplifier::optimizeStringMemoryLibCall(CallInst *CI,
return nullptr;
}
+/// Constant folding nan/nanf/nanl.
+static Value *optimizeNaN(CallInst *CI) {
+ StringRef CharSeq;
+ if (!getConstantStringInfo(CI->getArgOperand(0), CharSeq))
+ return nullptr;
+
+ llvm::APInt Fill;
+ // Treat empty strings as if they were zero.
+ if (CharSeq.empty())
+ Fill = llvm::APInt(32, 0);
+ else if (CharSeq.getAsInteger(0, Fill))
+ return nullptr;
+
+ return ConstantFP::getQNaN(CI->getType(), /*Negative=*/false, &Fill);
+}
+
Value *LibCallSimplifier::optimizeFloatingPointLibCall(CallInst *CI,
LibFunc Func,
IRBuilderBase &Builder) {
@@ -3972,6 +3988,10 @@ Value *LibCallSimplifier::optimizeFloatingPointLibCall(CallInst *CI,
case LibFunc_remquof:
case LibFunc_remquol:
return optimizeRemquo(CI, Builder);
+ case LibFunc_nan:
+ case LibFunc_nanf:
+ case LibFunc_nanl:
+ return optimizeNaN(CI);
default:
return nullptr;
}
diff --git a/llvm/test/Transforms/InstCombine/nan.ll b/llvm/test/Transforms/InstCombine/nan.ll
new file mode 100644
index 0000000000000..fd4119bc0c06a
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/nan.ll
@@ -0,0 +1,41 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+
+ at empty = private unnamed_addr constant [1 x i8] zeroinitializer, align 1
+ at dec = private unnamed_addr constant [2 x i8] c"1\00", align 1
+ at hex = private unnamed_addr constant [4 x i8] c"0xf\00", align 1
+
+define double @nan_empty() {
+; CHECK-LABEL: define double @nan_empty() {
+; CHECK-NEXT: ret double 0x7FF8000000000000
+;
+ %res = call double @nan(ptr @empty)
+ ret double %res
+}
+
+define double @nan_dec() {
+; CHECK-LABEL: define double @nan_dec() {
+; CHECK-NEXT: ret double 0x7FF8000000000001
+;
+ %res = call double @nan(ptr @dec)
+ ret double %res
+}
+
+define double @nan_hex() {
+; CHECK-LABEL: define double @nan_hex() {
+; CHECK-NEXT: ret double 0x7FF800000000000F
+;
+ %res = call double @nan(ptr @hex)
+ ret double %res
+}
+
+define float @nanf_empty() {
+; CHECK-LABEL: define float @nanf_empty() {
+; CHECK-NEXT: ret float 0x7FF8000000000000
+;
+ %res = call float @nanf(ptr @empty)
+ ret float %res
+}
+
+declare float @nanf(ptr)
+declare double @nan(ptr)
diff --git a/llvm/test/Transforms/InstCombine/nanl-fp128.ll b/llvm/test/Transforms/InstCombine/nanl-fp128.ll
new file mode 100644
index 0000000000000..21ba0fb14ca20
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/nanl-fp128.ll
@@ -0,0 +1,32 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+
+ at empty = private unnamed_addr constant [1 x i8] zeroinitializer, align 1
+ at dec = private unnamed_addr constant [2 x i8] c"1\00", align 1
+ at hex = private unnamed_addr constant [4 x i8] c"0xf\00", align 1
+
+define fp128 @nanl_empty() {
+; CHECK-LABEL: define fp128 @nanl_empty() {
+; CHECK-NEXT: ret fp128 0xL00000000000000007FFF800000000000
+;
+ %res = call fp128 @nanl(ptr @empty)
+ ret fp128 %res
+}
+
+define fp128 @nanl_dec() {
+; CHECK-LABEL: define fp128 @nanl_dec() {
+; CHECK-NEXT: ret fp128 0xL00000000000000017FFF800000000000
+;
+ %res = call fp128 @nanl(ptr @dec)
+ ret fp128 %res
+}
+
+define fp128 @nanl_hex() {
+; CHECK-LABEL: define fp128 @nanl_hex() {
+; CHECK-NEXT: ret fp128 0xL000000000000000F7FFF800000000000
+;
+ %res = call fp128 @nanl(ptr @hex)
+ ret fp128 %res
+}
+
+declare fp128 @nanl(ptr)
diff --git a/llvm/test/Transforms/InstCombine/nanl-fp80.ll b/llvm/test/Transforms/InstCombine/nanl-fp80.ll
new file mode 100644
index 0000000000000..7868af3696a56
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/nanl-fp80.ll
@@ -0,0 +1,32 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+
+ at empty = private unnamed_addr constant [1 x i8] zeroinitializer, align 1
+ at dec = private unnamed_addr constant [2 x i8] c"1\00", align 1
+ at hex = private unnamed_addr constant [4 x i8] c"0xf\00", align 1
+
+define x86_fp80 @nanl_empty() {
+; CHECK-LABEL: define x86_fp80 @nanl_empty() {
+; CHECK-NEXT: ret x86_fp80 0xK7FFFC000000000000000
+;
+ %res = call x86_fp80 @nanl(ptr @empty)
+ ret x86_fp80 %res
+}
+
+define x86_fp80 @nanl_dec() {
+; CHECK-LABEL: define x86_fp80 @nanl_dec() {
+; CHECK-NEXT: ret x86_fp80 0xK7FFFC000000000000001
+;
+ %res = call x86_fp80 @nanl(ptr @dec)
+ ret x86_fp80 %res
+}
+
+define x86_fp80 @nanl_hex() {
+; CHECK-LABEL: define x86_fp80 @nanl_hex() {
+; CHECK-NEXT: ret x86_fp80 0xK7FFFC00000000000000F
+;
+ %res = call x86_fp80 @nanl(ptr @hex)
+ ret x86_fp80 %res
+}
+
+declare x86_fp80 @nanl(ptr)
diff --git a/llvm/test/Transforms/InstCombine/nanl-ppc-fp128.ll b/llvm/test/Transforms/InstCombine/nanl-ppc-fp128.ll
new file mode 100644
index 0000000000000..7f60a379c4885
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/nanl-ppc-fp128.ll
@@ -0,0 +1,32 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+
+ at empty = private unnamed_addr constant [1 x i8] zeroinitializer, align 1
+ at dec = private unnamed_addr constant [2 x i8] c"1\00", align 1
+ at hex = private unnamed_addr constant [4 x i8] c"0xf\00", align 1
+
+define ppc_fp128 @nanl_empty() {
+; CHECK-LABEL: define ppc_fp128 @nanl_empty() {
+; CHECK-NEXT: ret ppc_fp128 0xM7FF80000000000000000000000000000
+;
+ %res = call ppc_fp128 @nanl(ptr @empty)
+ ret ppc_fp128 %res
+}
+
+define ppc_fp128 @nanl_dec() {
+; CHECK-LABEL: define ppc_fp128 @nanl_dec() {
+; CHECK-NEXT: ret ppc_fp128 0xM7FF80000000000010000000000000000
+;
+ %res = call ppc_fp128 @nanl(ptr @dec)
+ ret ppc_fp128 %res
+}
+
+define ppc_fp128 @nanl_hex() {
+; CHECK-LABEL: define ppc_fp128 @nanl_hex() {
+; CHECK-NEXT: ret ppc_fp128 0xM7FF800000000000F0000000000000000
+;
+ %res = call ppc_fp128 @nanl(ptr @hex)
+ ret ppc_fp128 %res
+}
+
+declare ppc_fp128 @nanl(ptr)
``````````
</details>
https://github.com/llvm/llvm-project/pull/101459
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