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ac: generate FMA for inexact instructions for radeonsi 

NIR mostly does this already.

Totals:
SGPRS: 2588520 -> 2591784 (0.13 %)
VGPRS: 1666984 -> 1666888 (-0.01 %)
Spilled SGPRs: 4074 -> 4131 (1.40 %)
Spilled VGPRs: 38 -> 38 (0.00 %)
Private memory VGPRs: 2176 -> 2176 (0.00 %)
Scratch size: 2228 -> 2228 (0.00 %) dwords per thread
Code Size: 52726872 -> 52715468 (-0.02 %) bytes
LDS: 92 -> 92 (0.00 %) blocks
Max Waves: 479872 -> 479897 (0.01 %)
Wait states: 0 -> 0 (0.00 %)

Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4696>
This commit is contained in:
Marek Olšák 2020-04-22 22:45:45 -04:00 committed by Marge Bot
parent f2c2a28073
commit 4b9370cb0f
3 changed files with 40 additions and 0 deletions
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31
src/amd/llvm/ac_llvm_helper.cpp
View File

@ -96,6 +96,11 @@ LLVMBuilderRef ac_create_builder(LLVMContextRef ctx,
*/
flags.setAllowReciprocal(); /* arcp */
/* Allow floating-point contraction (e.g. fusing a multiply
* followed by an addition into a fused multiply-and-add).
*/
flags.setAllowContract(); /* contract */
llvm::unwrap(builder)->setFastMathFlags(flags);
break;
}
@ -103,6 +108,32 @@ LLVMBuilderRef ac_create_builder(LLVMContextRef ctx,
return builder;
}
/* Return the original state of inexact math. */
bool ac_disable_inexact_math(LLVMBuilderRef builder)
{
auto *b = llvm::unwrap(builder);
llvm::FastMathFlags flags = b->getFastMathFlags();
if (!flags.allowContract())
return false;
flags.setAllowContract(false);
b->setFastMathFlags(flags);
return true;
}
void ac_restore_inexact_math(LLVMBuilderRef builder, bool value)
{
auto *b = llvm::unwrap(builder);
llvm::FastMathFlags flags = b->getFastMathFlags();
if (flags.allowContract() == value)
return;
flags.setAllowContract(value);
b->setFastMathFlags(flags);
}
LLVMTargetLibraryInfoRef
ac_create_target_library_info(const char *triple)
{

2
src/amd/llvm/ac_llvm_util.h
View File

@ -109,6 +109,8 @@ LLVMModuleRef ac_create_module(LLVMTargetMachineRef tm, LLVMContextRef ctx);
LLVMBuilderRef ac_create_builder(LLVMContextRef ctx,
enum ac_float_mode float_mode);
bool ac_disable_inexact_math(LLVMBuilderRef builder);
void ac_restore_inexact_math(LLVMBuilderRef builder, bool value);
void
ac_llvm_add_target_dep_function_attr(LLVMValueRef F,

7
src/amd/llvm/ac_nir_to_llvm.c
View File

@ -589,6 +589,10 @@ static void visit_alu(struct ac_nir_context *ctx, const nir_alu_instr *instr)
unsigned num_components = instr->dest.dest.ssa.num_components;
unsigned src_components;
LLVMTypeRef def_type = get_def_type(ctx, &instr->dest.dest.ssa);
bool saved_inexact = false;
if (instr->exact)
saved_inexact = ac_disable_inexact_math(ctx->ac.builder);
assert(nir_op_infos[instr->op].num_inputs <= ARRAY_SIZE(src));
switch (instr->op) {
@ -1182,6 +1186,9 @@ static void visit_alu(struct ac_nir_context *ctx, const nir_alu_instr *instr)
result = ac_to_integer_or_pointer(&ctx->ac, result);
ctx->ssa_defs[instr->dest.dest.ssa.index] = result;
}
if (instr->exact)
ac_restore_inexact_math(ctx->ac.builder, saved_inexact);
}
static void visit_load_const(struct ac_nir_context *ctx,