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[PowerPC] Replace subtract-from-zero float in version with fneg in PowerPC special fma compiler builtins 

This patch adds a test for the PowerPC fma compiler builtins, some variations
of which negate inputs and outputs. The code to generate IR for these
builtins was untested before this patch.

Originally, the code used the outdated method of subtracting floating point
values from -0.0 as floating point negation. This patch remedies that.

Patch by: Drew Wock <drew.wock@sas.com>
Differential Revision: https://reviews.llvm.org/D76949
This commit is contained in:
Andrew Wock 2020-04-03 14:55:27 -04:00 committed by Kevin P. Neal
parent 9657446313
commit ba87430cad
2 changed files with 50 additions and 8 deletions
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15
clang/lib/CodeGen/CGBuiltin.cpp
View File

@ -13214,25 +13214,24 @@ Value *CodeGenFunction::EmitPPCBuiltinExpr(unsigned BuiltinID,
Value *X = EmitScalarExpr(E->getArg(0));
Value *Y = EmitScalarExpr(E->getArg(1));
Value *Z = EmitScalarExpr(E->getArg(2));
Value *Zero = llvm::ConstantFP::getZeroValueForNegation(ResultType);
llvm::Function *F = CGM.getIntrinsic(Intrinsic::fma, ResultType);
switch (BuiltinID) {
case PPC::BI__builtin_vsx_xvmaddadp:
case PPC::BI__builtin_vsx_xvmaddasp:
return Builder.CreateCall(F, {X, Y, Z});
case PPC::BI__builtin_vsx_xvnmaddadp:
case PPC::BI__builtin_vsx_xvnmaddasp:
return Builder.CreateFSub(Zero,
Builder.CreateCall(F, {X, Y, Z}), "sub");
return Builder.CreateFNeg(Builder.CreateCall(F, {X, Y, Z}), "neg");
case PPC::BI__builtin_vsx_xvmsubadp:
case PPC::BI__builtin_vsx_xvmsubasp:
return Builder.CreateCall(F,
{X, Y, Builder.CreateFSub(Zero, Z, "sub")});
return Builder.CreateCall(F, {X, Y, Builder.CreateFNeg(Z, "neg")});
case PPC::BI__builtin_vsx_xvnmsubadp:
case PPC::BI__builtin_vsx_xvnmsubasp:
Value *FsubRes =
Builder.CreateCall(F, {X, Y, Builder.CreateFSub(Zero, Z, "sub")});
return Builder.CreateFSub(Zero, FsubRes, "sub");
return Builder.CreateFNeg(
Builder.CreateCall(F, {X, Y, Builder.CreateFNeg(Z, "neg")}), "neg");
}
llvm_unreachable("Unknown FMA operation");
return nullptr; // Suppress no-return warning

43
clang/test/CodeGen/builtins-ppc-fma.c Normal file
View File

@ -0,0 +1,43 @@
// RUN: %clang_cc1 -triple powerpc64le-gnu-linux \
// RUN: -target-feature +altivec -Wall -Wno-unused -Werror -emit-llvm %s -o - | FileCheck \
// RUN: %s
typedef __attribute__((vector_size(4 * sizeof(float)))) float vec_float;
typedef __attribute__((vector_size(2 * sizeof(double)))) double vec_double;
volatile vec_double vd;
volatile vec_float vf;
void test_fma(void) {
vf = __builtin_vsx_xvmaddasp(vf, vf, vf);
// CHECK: @llvm.fma.v4f32(<4 x float> %{{.*}}, <4 x float> %{{.*}}, <4 x float> %{{.*}})
vd = __builtin_vsx_xvmaddadp(vd, vd, vd);
// CHECK: @llvm.fma.v2f64(<2 x double> %{{.*}}, <2 x double> %{{.*}}, <2 x double> %{{.*}})
vf = __builtin_vsx_xvnmaddasp(vf, vf, vf);
// CHECK: [[RESULT:%[^ ]+]] = call <4 x float> @llvm.fma.v4f32(<4 x float> %{{.*}}, <4 x float> %{{.*}}, <4 x float> %{{.*}})
// CHECK: fneg <4 x float> [[RESULT]]
vd = __builtin_vsx_xvnmaddadp(vd, vd, vd);
// CHECK: [[RESULT:%[^ ]+]] = call <2 x double> @llvm.fma.v2f64(<2 x double> %{{.*}}, <2 x double> %{{.*}}, <2 x double> %{{.*}})
// CHECK: fneg <2 x double> [[RESULT]]
vf = __builtin_vsx_xvmsubasp(vf, vf, vf);
// CHECK: [[RESULT:%[^ ]+]] fneg <4 x float> %{{.*}}
// CHECK: @llvm.fma.v4f32(<4 x float> %{{.*}}, <4 x float> %{{.*}}, <4 x float> [[RESULT]])
vd = __builtin_vsx_xvmsubadp(vd, vd, vd);
// CHECK: fneg <2 x double> [[RESULT]]
// CHECK: [[RESULT:%[^ ]+]] = call <2 x double> @llvm.fma.v2f64(<2 x double> %{{.*}}, <2 x double> %{{.*}}, <2 x double> %{{.*}})
vf = __builtin_vsx_xvnmsubasp(vf, vf, vf);
// CHECK: [[RESULT:%[^ ]+]] = fneg <4 x float> %{{.*}}
// CHECK: [[RESULT2:%[^ ]+]] = call <4 x float> @llvm.fma.v2f64(<4 x float> %{{.*}}, <4 x float> %{{.*}}, <4 x float> [[RESULT]])
// CHECK: fneg <4 x float> [[RESULT2]]
vd = __builtin_vsx_xvnmsubadp(vd, vd, vd);
// CHECK: [[RESULT:%[^ ]+]] = fneg <2 x double> %{{.*}}
// CHECK: [[RESULT2:%[^ ]+]] = call <2 x double> @llvm.fma.v2f64(<2 x double> %{{.*}}, <2 x double> %{{.*}}, <2 x double> [[RESULT]])
// CHECK: fneg <2 x double> [[RESULT2]]
}