diff options
| -rw-r--r-- | src/amd/compiler/README | 33 | ||||
| -rw-r--r-- | src/amd/compiler/aco_assembler.cpp | 6 |
2 files changed, 37 insertions, 2 deletions
diff --git a/src/amd/compiler/README b/src/amd/compiler/README index 16e7daee3e4..630f1fcd42a 100644 --- a/src/amd/compiler/README +++ b/src/amd/compiler/README @@ -140,3 +140,36 @@ by an `s_buffer_store` with the same address. Inserting an `s_nop` between them does not mitigate the issue, so an `s_waitcnt lgkmcnt(0)` must be inserted. This is not mentioned by LLVM among the other GFX10 bugs, but LLVM doesn't use SMEM stores, so it's not surprising that they didn't notice it. + +### VMEMtoScalarWriteHazard + +Triggered by: +VMEM/FLAT/GLOBAL/SCRATCH/DS instruction reads an SGPR (or EXEC, or M0). +Then, a SALU/SMEM instruction writes the same SGPR. + +Mitigated by: +A VALU instruction or an `s_waitcnt vmcnt(0)` between the two instructions. + +### Offset3fBug + +Any branch that is located at offset 0x3f will be buggy. Just insert some NOPs to make sure no branch +is located at this offset. + +### InstFwdPrefetchBug + +According to LLVM, the `s_inst_prefetch` instruction can cause a hang. +There are no further details. + +### LdsMisalignedBug + +When there is a misaligned multi-dword FLAT load/store instruction in WGP mode, +it needs to be split into multiple single-dword FLAT instructions. + +ACO doesn't use FLAT load/store on GFX10, so is unaffected. + +### FlatSegmentOffsetBug + +The 12-bit immediate OFFSET field of FLAT instructions must always be 0. +GLOBAL and SCRATCH are unaffected. + +ACO doesn't use FLAT load/store on GFX10, so is unaffected. diff --git a/src/amd/compiler/aco_assembler.cpp b/src/amd/compiler/aco_assembler.cpp index ea7295816db..08debb25ad6 100644 --- a/src/amd/compiler/aco_assembler.cpp +++ b/src/amd/compiler/aco_assembler.cpp @@ -399,8 +399,10 @@ void emit_instruction(asm_context& ctx, std::vector<uint32_t>& out, Instruction* assert(flat->offset <= 0x1fff); encoding |= flat->offset & 0x1fff; } else { - assert(flat->offset <= 0x0fff); - encoding |= flat->offset & 0x0fff; + /* GFX10 has a 12-bit immediate OFFSET field, + * but it has a hw bug: it ignores the offset, called FlatSegmentOffsetBug + */ + assert(flat->offset == 0); } if (instr->format == Format::SCRATCH) encoding |= 1 << 14; |