aco/gfx10: Fix VcmpxExecWARHazard mitigation.

The SOPP instruction shouldn't have a definition, and its block
should be set to -1 in order to prevent it from being recognized
as a branch.
Also fix a typo in the readme.

Fixes: d6dfce02d074d615a3b88a3fccd8ee8c7e13c010
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Rhys Perry <pendingchaos02@gmail.com>
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3552>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3552>

diff --git a/src/amd/compiler/README.md b/src/amd/compiler/README.md
index 822ecd7..7c7e68f 100644 (file)
--- a/src/amd/compiler/README.md
+++ b/src/amd/compiler/README.md
@@ -154,7 +154,6 @@ A VALU instruction or an `s_waitcnt vmcnt(0)` between the two instructions.
 
 Triggered by:
 An SMEM instruction reads an SGPR. Then, a VALU instruction writes that same SGPR.
-Despite LLVM
 
 Mitigated by:
 Any non-SOPP SALU instruction (except `s_setvskip`, `s_version`, and any non-lgkmcnt `s_waitcnt`).

diff --git a/src/amd/compiler/aco_insert_NOPs.cpp b/src/amd/compiler/aco_insert_NOPs.cpp
index b9eaaed..689d5e2 100644 (file)
--- a/src/amd/compiler/aco_insert_NOPs.cpp
+++ b/src/amd/compiler/aco_insert_NOPs.cpp
@@ -491,9 +491,9 @@ void handle_instruction_gfx10(Program *program, NOP_ctx_gfx10 &ctx, aco_ptr<Inst
          ctx.has_nonVALU_exec_read = false;
 
          /* Insert s_waitcnt_depctr instruction with magic imm to mitigate the problem */
-         aco_ptr<SOPP_instruction> depctr{create_instruction<SOPP_instruction>(aco_opcode::s_waitcnt_depctr, Format::SOPP, 0, 1)};
+         aco_ptr<SOPP_instruction> depctr{create_instruction<SOPP_instruction>(aco_opcode::s_waitcnt_depctr, Format::SOPP, 0, 0)};
          depctr->imm = 0xfffe;
-         depctr->definitions[0] = Definition(sgpr_null, s1);
+         depctr->block = -1;
          new_instructions.emplace_back(std::move(depctr));
       } else if (instr_writes_sgpr(instr)) {
          /* Any VALU instruction that writes an SGPR mitigates the problem */