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aco: workaround GFX10 0x3f branch bug

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According to LLVM, branches with an offset of 0x3f are buggy.

v2: (by Timur Kristóf)
- extract the GFX10 specific part to its own function

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
This commit is contained in:
Rhys Perry 2019-09-10 18:11:13 +01:00 • committed by Timur Kristóf
parent 0be1dd8564
commit 83993f535e
1 changed files with 39 additions and 5 deletions
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44
src/amd/compiler/aco_assembler.cpp
View file

@ -1,4 +1,5 @@
#include <map>
#include <vector>
#include <algorithm>
#include "aco_ir.h"
#include "common/sid.h"
@ -9,7 +10,7 @@ namespace aco {
struct asm_context {
Program *program;
enum chip_class chip_class;
std::map<int, SOPP_instruction*> branches;
std::vector<std::pair<int, SOPP_instruction*>> branches;
std::vector<unsigned> constaddrs;
const int16_t* opcode;
// TODO: keep track of branch instructions referring blocks
@ -135,7 +136,7 @@ void emit_instruction(asm_context& ctx, std::vector<uint32_t>& out, Instruction*
encoding |= opcode << 16;
encoding |= (uint16_t) sopp->imm;
if (sopp->block != -1)
ctx.branches.insert({out.size(), sopp});
ctx.branches.emplace_back(out.size(), sopp);
out.push_back(encoding);
break;
}
@ -605,10 +606,43 @@ void fix_exports(asm_context& ctx, std::vector<uint32_t>& out, Program* program)
}
}
static void fix_branches_gfx10(asm_context& ctx, std::vector<uint32_t>& out)
{
/* Branches with an offset of 0x3f are buggy on GFX10, we workaround by inserting NOPs if needed. */
bool gfx10_3f_bug = false;
do {
auto buggy_branch_it = std::find_if(ctx.branches.begin(), ctx.branches.end(), [&ctx](const auto &branch) -> bool {
return ((int)ctx.program->blocks[branch.second->block].offset - branch.first - 1) == 0x3f;
});
gfx10_3f_bug = buggy_branch_it != ctx.branches.end();
if (gfx10_3f_bug) {
/* Insert an s_nop after the branch */
constexpr uint32_t s_nop_0 = 0xbf800000u;
auto out_pos = std::next(out.begin(), buggy_branch_it->first + 1);
out.insert(out_pos, s_nop_0);
/* Update the offset of each affected block */
for (Block& block : ctx.program->blocks) {
if (block.offset > (unsigned)buggy_branch_it->first)
block.offset++;
}
/* Update the branches following the current one */
for (auto branch_it = std::next(buggy_branch_it); branch_it != ctx.branches.end(); ++branch_it)
branch_it->first++;
}
} while (gfx10_3f_bug);
}
void fix_branches(asm_context& ctx, std::vector<uint32_t>& out)
{
for (std::pair<int, SOPP_instruction*> branch : ctx.branches)
{
if (ctx.chip_class >= GFX10)
fix_branches_gfx10(ctx, out);
for (std::pair<int, SOPP_instruction*> &branch : ctx.branches) {
int offset = (int)ctx.program->blocks[branch.second->block].offset - branch.first - 1;
out[branch.first] |= (uint16_t) offset;
}