r317031 - [CodeGen] map sqrt libcalls to llvm.sqrt when errno is not set
Sanjay Patel via cfe-commits
cfe-commits at lists.llvm.org
Tue Oct 31 13:19:40 PDT 2017
Author: spatel
Date: Tue Oct 31 13:19:39 2017
New Revision: 317031
URL: http://llvm.org/viewvc/llvm-project?rev=317031&view=rev
Log:
[CodeGen] map sqrt libcalls to llvm.sqrt when errno is not set
The LLVM sqrt intrinsic definition changed with:
D28797
...so we don't have to use any relaxed FP settings other than errno handling.
This patch sidesteps a question raised in PR27435:
https://bugs.llvm.org/show_bug.cgi?id=27435
Is a programmer using __builtin_sqrt() invoking the compiler's intrinsic definition of sqrt or the mathlib definition of sqrt?
But we have an answer now: the builtin should match the behavior of the libm function including errno handling.
Differential Revision: https://reviews.llvm.org/D39204
Added:
cfe/trunk/test/CodeGen/builtin-sqrt.c
- copied, changed from r317030, cfe/trunk/test/CodeGen/2005-07-20-SqrtNoErrno.c
Removed:
cfe/trunk/test/CodeGen/2005-07-20-SqrtNoErrno.c
Modified:
cfe/trunk/lib/CodeGen/CGBuiltin.cpp
cfe/trunk/test/CodeGen/libcalls.c
Modified: cfe/trunk/lib/CodeGen/CGBuiltin.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGBuiltin.cpp?rev=317031&r1=317030&r2=317031&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGBuiltin.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGBuiltin.cpp Tue Oct 31 13:19:39 2017
@@ -2072,24 +2072,21 @@ RValue CodeGenFunction::EmitBuiltinExpr(
return RValue::get(nullptr);
}
- // Library functions with special handling.
case Builtin::BIsqrt:
case Builtin::BIsqrtf:
- case Builtin::BIsqrtl: {
- // Transform a call to sqrt* into a @llvm.sqrt.* intrinsic call, but only
- // in finite- or unsafe-math mode (the intrinsic has different semantics
- // for handling negative numbers compared to the library function, so
- // -fmath-errno=0 is not enough).
- if (!FD->hasAttr<ConstAttr>())
- break;
- if (!(CGM.getCodeGenOpts().UnsafeFPMath ||
- CGM.getCodeGenOpts().NoNaNsFPMath))
- break;
- Value *Arg0 = EmitScalarExpr(E->getArg(0));
- llvm::Type *ArgType = Arg0->getType();
- Value *F = CGM.getIntrinsic(Intrinsic::sqrt, ArgType);
- return RValue::get(Builder.CreateCall(F, Arg0));
- }
+ case Builtin::BIsqrtl:
+ // Builtins have the same semantics as library functions. The LLVM intrinsic
+ // has the same semantics as the library function except it does not set
+ // errno. Thus, we can transform either sqrt or __builtin_sqrt to @llvm.sqrt
+ // if the call is 'const' (the call must not set errno).
+ //
+ // FIXME: The builtin cases are not here because they are marked 'const' in
+ // Builtins.def. So that means they are wrongly defined to have different
+ // semantics than the library functions. If we included them here, we would
+ // turn them into LLVM intrinsics regardless of whether -fmath-errno was on.
+ if (FD->hasAttr<ConstAttr>())
+ return RValue::get(emitUnaryBuiltin(*this, E, Intrinsic::sqrt));
+ break;
case Builtin::BI__builtin_pow:
case Builtin::BI__builtin_powf:
Removed: cfe/trunk/test/CodeGen/2005-07-20-SqrtNoErrno.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/2005-07-20-SqrtNoErrno.c?rev=317030&view=auto
==============================================================================
--- cfe/trunk/test/CodeGen/2005-07-20-SqrtNoErrno.c (original)
+++ cfe/trunk/test/CodeGen/2005-07-20-SqrtNoErrno.c (removed)
@@ -1,10 +0,0 @@
-// RUN: %clang_cc1 -triple x86_64-apple-darwin %s -emit-llvm -o - | FileCheck %s
-// llvm.sqrt has undefined behavior on negative inputs, so it is
-// inappropriate to translate C/C++ sqrt to this.
-float sqrtf(float x);
-float foo(float X) {
- // CHECK: foo
- // CHECK: call float @sqrtf(float %
- // Check that this is marked readonly when errno is ignored.
- return sqrtf(X);
-}
Copied: cfe/trunk/test/CodeGen/builtin-sqrt.c (from r317030, cfe/trunk/test/CodeGen/2005-07-20-SqrtNoErrno.c)
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/builtin-sqrt.c?p2=cfe/trunk/test/CodeGen/builtin-sqrt.c&p1=cfe/trunk/test/CodeGen/2005-07-20-SqrtNoErrno.c&r1=317030&r2=317031&rev=317031&view=diff
==============================================================================
--- cfe/trunk/test/CodeGen/2005-07-20-SqrtNoErrno.c (original)
+++ cfe/trunk/test/CodeGen/builtin-sqrt.c Tue Oct 31 13:19:39 2017
@@ -1,10 +1,19 @@
-// RUN: %clang_cc1 -triple x86_64-apple-darwin %s -emit-llvm -o - | FileCheck %s
-// llvm.sqrt has undefined behavior on negative inputs, so it is
-// inappropriate to translate C/C++ sqrt to this.
-float sqrtf(float x);
+// RUN: %clang_cc1 -fmath-errno -triple x86_64-apple-darwin %s -emit-llvm -o - | FileCheck %s --check-prefix=HAS_ERRNO
+// RUN: %clang_cc1 -triple x86_64-apple-darwin %s -emit-llvm -o - | FileCheck %s --check-prefix=NO_ERRNO
+
+// FIXME: If a builtin is supposed to have identical semantics to its libm twin, then it
+// should not be marked "constant" in Builtins.def because that means it can't set errno.
+// Note that both runs have 'readnone' on the libcall here.
+
float foo(float X) {
- // CHECK: foo
- // CHECK: call float @sqrtf(float %
- // Check that this is marked readonly when errno is ignored.
- return sqrtf(X);
+ // HAS_ERRNO: call float @sqrtf(float
+ // NO_ERRNO: call float @sqrtf(float
+ return __builtin_sqrtf(X);
}
+
+// HAS_ERRNO: declare float @sqrtf(float) [[ATTR:#[0-9]+]]
+// HAS_ERRNO: attributes [[ATTR]] = { nounwind readnone {{.*}}}
+
+// NO_ERRNO: declare float @sqrtf(float) [[ATTR:#[0-9]+]]
+// NO_ERRNO: attributes [[ATTR]] = { nounwind readnone {{.*}}}
+
Modified: cfe/trunk/test/CodeGen/libcalls.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/libcalls.c?rev=317031&r1=317030&r2=317031&view=diff
==============================================================================
--- cfe/trunk/test/CodeGen/libcalls.c (original)
+++ cfe/trunk/test/CodeGen/libcalls.c Tue Oct 31 13:19:39 2017
@@ -6,29 +6,28 @@
// CHECK-NO-LABEL: define void @test_sqrt
// CHECK-FAST-LABEL: define void @test_sqrt
void test_sqrt(float a0, double a1, long double a2) {
- // Following llvm-gcc's lead, we never emit these as intrinsics;
- // no-math-errno isn't good enough. We could probably use intrinsics
- // with appropriate guards if it proves worthwhile.
-
// CHECK-YES: call float @sqrtf
- // CHECK-NO: call float @sqrtf
+ // CHECK-NO: call float @llvm.sqrt.f32(float
+ // CHECK-FAST: call float @llvm.sqrt.f32(float
float l0 = sqrtf(a0);
// CHECK-YES: call double @sqrt
- // CHECK-NO: call double @sqrt
+ // CHECK-NO: call double @llvm.sqrt.f64(double
+ // CHECK-FAST: call double @llvm.sqrt.f64(double
double l1 = sqrt(a1);
// CHECK-YES: call x86_fp80 @sqrtl
- // CHECK-NO: call x86_fp80 @sqrtl
+ // CHECK-NO: call x86_fp80 @llvm.sqrt.f80(x86_fp80
+ // CHECK-FAST: call x86_fp80 @llvm.sqrt.f80(x86_fp80
long double l2 = sqrtl(a2);
}
// CHECK-YES: declare float @sqrtf(float)
// CHECK-YES: declare double @sqrt(double)
// CHECK-YES: declare x86_fp80 @sqrtl(x86_fp80)
-// CHECK-NO: declare float @sqrtf(float) [[NUW_RN:#[0-9]+]]
-// CHECK-NO: declare double @sqrt(double) [[NUW_RN]]
-// CHECK-NO: declare x86_fp80 @sqrtl(x86_fp80) [[NUW_RN]]
+// CHECK-NO: declare float @llvm.sqrt.f32(float)
+// CHECK-NO: declare double @llvm.sqrt.f64(double)
+// CHECK-NO: declare x86_fp80 @llvm.sqrt.f80(x86_fp80)
// CHECK-FAST: declare float @llvm.sqrt.f32(float)
// CHECK-FAST: declare double @llvm.sqrt.f64(double)
// CHECK-FAST: declare x86_fp80 @llvm.sqrt.f80(x86_fp80)
@@ -86,7 +85,7 @@ void test_builtins(double d, float f, lo
double atan_ = atan(d);
long double atanl_ = atanl(ld);
float atanf_ = atanf(f);
-// CHECK-NO: declare double @atan(double) [[NUW_RN]]
+// CHECK-NO: declare double @atan(double) [[NUW_RN:#[0-9]+]]
// CHECK-NO: declare x86_fp80 @atanl(x86_fp80) [[NUW_RN]]
// CHECK-NO: declare float @atanf(float) [[NUW_RN]]
// CHECK-YES-NOT: declare double @atan(double) [[NUW_RN]]
@@ -126,5 +125,5 @@ void test_builtins(double d, float f, lo
// CHECK-YES: attributes [[NUW_RN]] = { nounwind readnone speculatable }
-// CHECK-NO: attributes [[NUW_RN]] = { nounwind readnone{{.*}} }
-// CHECK-NO: attributes [[NUW_RNI]] = { nounwind readnone speculatable }
+// CHECK-NO-DAG: attributes [[NUW_RN]] = { nounwind readnone{{.*}} }
+// CHECK-NO-DAG: attributes [[NUW_RNI]] = { nounwind readnone speculatable }
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