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Rollup merge of #62828 - nikic:fadd-mul-reductions, r=eddyb

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Remove vector fadd/fmul reduction workarounds

The bugs that this was working around have been fixed in LLVM 9.

r? @gnzlbg
This commit is contained in:
Mazdak Farrokhzad
2019-07-26 18:56:45 +02:00
committed by GitHub
parent 632ce7402f 6fae7db65d
commit 5ffdca77c4
7 changed files with 37 additions and 102 deletions
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12
src/librustc_codegen_llvm/builder.rs
View File

@@ -1153,11 +1153,14 @@ impl Builder<'a, 'll, 'tcx> {
}
}
pub fn vector_reduce_fadd(&mut self, acc: &'ll Value, src: &'ll Value) -> &'ll Value {
unsafe { llvm::LLVMRustBuildVectorReduceFAdd(self.llbuilder, acc, src) }
}
pub fn vector_reduce_fmul(&mut self, acc: &'ll Value, src: &'ll Value) -> &'ll Value {
unsafe { llvm::LLVMRustBuildVectorReduceFMul(self.llbuilder, acc, src) }
}
pub fn vector_reduce_fadd_fast(&mut self, acc: &'ll Value, src: &'ll Value) -> &'ll Value {
unsafe {
// FIXME: add a non-fast math version once
// https://bugs.llvm.org/show_bug.cgi?id=36732
// is fixed.
let instr = llvm::LLVMRustBuildVectorReduceFAdd(self.llbuilder, acc, src);
llvm::LLVMRustSetHasUnsafeAlgebra(instr);
instr
@@ -1165,9 +1168,6 @@ impl Builder<'a, 'll, 'tcx> {
}
pub fn vector_reduce_fmul_fast(&mut self, acc: &'ll Value, src: &'ll Value) -> &'ll Value {
unsafe {
// FIXME: add a non-fast math version once
// https://bugs.llvm.org/show_bug.cgi?id=36732
// is fixed.
let instr = llvm::LLVMRustBuildVectorReduceFMul(self.llbuilder, acc, src);
llvm::LLVMRustSetHasUnsafeAlgebra(instr);
instr

19
src/librustc_codegen_llvm/common.rs
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@@ -166,25 +166,6 @@ impl CodegenCx<'ll, 'tcx> {
r
}
}
pub fn const_get_real(&self, v: &'ll Value) -> Option<(f64, bool)> {
unsafe {
if self.is_const_real(v) {
let mut loses_info: llvm::Bool = 0;
let r = llvm::LLVMConstRealGetDouble(v, &mut loses_info);
let loses_info = if loses_info == 1 { true } else { false };
Some((r, loses_info))
} else {
None
}
}
}
fn is_const_real(&self, v: &'ll Value) -> bool {
unsafe {
llvm::LLVMIsAConstantFP(v).is_some()
}
}
}
impl ConstMethods<'tcx> for CodegenCx<'ll, 'tcx> {

28
src/librustc_codegen_llvm/intrinsic.rs
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@@ -1640,29 +1640,11 @@ fn generic_simd_intrinsic(
}
},
ty::Float(f) => {
// ordered arithmetic reductions take an accumulator
let acc = if $ordered {
let acc = args[1].immediate();
// FIXME: https://bugs.llvm.org/show_bug.cgi?id=36734
// * if the accumulator of the fadd isn't 0, incorrect
// code is generated
// * if the accumulator of the fmul isn't 1, incorrect
// code is generated
match bx.const_get_real(acc) {
None => return_error!("accumulator of {} is not a constant", $name),
Some((v, loses_info)) => {
if $name.contains("mul") && v != 1.0_f64 {
return_error!("accumulator of {} is not 1.0", $name);
} else if $name.contains("add") && v != 0.0_f64 {
return_error!("accumulator of {} is not 0.0", $name);
} else if loses_info {
return_error!("accumulator of {} loses information", $name);
}
}
}
acc
// ordered arithmetic reductions take an accumulator
args[1].immediate()
} else {
// unordered arithmetic reductions do not:
// unordered arithmetic reductions use the identity accumulator
let identity_acc = if $name.contains("mul") { 1.0 } else { 0.0 };
match f.bit_width() {
32 => bx.const_real(bx.type_f32(), identity_acc),
@@ -1688,8 +1670,8 @@ unsupported {} from `{}` with element `{}` of size `{}` to `{}`"#,
}
}
arith_red!("simd_reduce_add_ordered": vector_reduce_add, vector_reduce_fadd_fast, true);
arith_red!("simd_reduce_mul_ordered": vector_reduce_mul, vector_reduce_fmul_fast, true);
arith_red!("simd_reduce_add_ordered": vector_reduce_add, vector_reduce_fadd, true);
arith_red!("simd_reduce_mul_ordered": vector_reduce_mul, vector_reduce_fmul, true);
arith_red!("simd_reduce_add_unordered": vector_reduce_add, vector_reduce_fadd_fast, false);
arith_red!("simd_reduce_mul_unordered": vector_reduce_mul, vector_reduce_fmul_fast, false);

2
src/librustc_codegen_llvm/llvm/ffi.rs
View File

@@ -719,7 +719,6 @@ extern "C" {
pub fn LLVMConstIntGetZExtValue(ConstantVal: &Value) -> c_ulonglong;
pub fn LLVMRustConstInt128Get(ConstantVal: &Value, SExt: bool,
high: &mut u64, low: &mut u64) -> bool;
pub fn LLVMConstRealGetDouble (ConstantVal: &Value, losesInfo: &mut Bool) -> f64;
// Operations on composite constants
@@ -1663,7 +1662,6 @@ extern "C" {
pub fn LLVMRustWriteValueToString(value_ref: &Value, s: &RustString);
pub fn LLVMIsAConstantInt(value_ref: &Value) -> Option<&Value>;
pub fn LLVMIsAConstantFP(value_ref: &Value) -> Option<&Value>;
pub fn LLVMRustPassKind(Pass: &Pass) -> PassKind;
pub fn LLVMRustFindAndCreatePass(Pass: *const c_char) -> Option<&'static mut Pass>;