From e192e268deb4ad27baa4bdcbaa0f4fe23086ae2e Mon Sep 17 00:00:00 2001
From: Rhys Perry <pendingchaos02@gmail.com>
Date: Fri, 15 Nov 2019 11:43:19 +0000
Subject: [PATCH] aco: explicitly mark end blocks for exports
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For GS copy shaders, whether we want to do exports is conditional. By
explicitly marking the end blocks, we can mark an IF's then branch as an
export block and ensure that's where the assembler inserts null exports.

v6: only fixup exports in the end block, like before
v8: simplify some code

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/2421>
---
 src/amd/compiler/aco_assembler.cpp             | 17 ++++++-----------
 src/amd/compiler/aco_instruction_selection.cpp |  2 +-
 src/amd/compiler/aco_ir.h                      |  1 +
 3 files changed, 8 insertions(+), 12 deletions(-)

diff --git a/src/amd/compiler/aco_assembler.cpp b/src/amd/compiler/aco_assembler.cpp
index c7088a498b5..94c41173d6e 100644
--- a/src/amd/compiler/aco_assembler.cpp
+++ b/src/amd/compiler/aco_assembler.cpp
@@ -595,14 +595,14 @@ void emit_block(asm_context& ctx, std::vector<uint32_t>& out, Block& block)
 
 void fix_exports(asm_context& ctx, std::vector<uint32_t>& out, Program* program)
 {
-   for (int idx = program->blocks.size() - 1; idx >= 0; idx--) {
-      Block& block = program->blocks[idx];
+   for (Block& block : program->blocks) {
+      if (!(block.kind & block_kind_export_end))
+         continue;
       std::vector<aco_ptr<Instruction>>::reverse_iterator it = block.instructions.rbegin();
-      bool endBlock = false;
       bool exported = false;
       while ( it != block.instructions.rend())
       {
-         if ((*it)->format == Format::EXP && endBlock) {
+         if ((*it)->format == Format::EXP) {
             Export_instruction* exp = static_cast<Export_instruction*>((*it).get());
             if (program->stage & hw_vs) {
                if (exp->dest >= V_008DFC_SQ_EXP_POS && exp->dest <= (V_008DFC_SQ_EXP_POS + 3)) {
@@ -618,14 +618,9 @@ void fix_exports(asm_context& ctx, std::vector<uint32_t>& out, Program* program)
             }
          } else if ((*it)->definitions.size() && (*it)->definitions[0].physReg() == exec)
             break;
-         else if ((*it)->opcode == aco_opcode::s_endpgm) {
-            if (endBlock)
-               break;
-            endBlock = true;
-         }
          ++it;
       }
-      if (!endBlock || exported)
+      if (exported)
          continue;
       /* we didn't find an Export instruction and have to insert a null export */
       aco_ptr<Export_instruction> exp{create_instruction<Export_instruction>(aco_opcode::exp, Format::EXP, 4, 0)};
@@ -639,7 +634,7 @@ void fix_exports(asm_context& ctx, std::vector<uint32_t>& out, Program* program)
          exp->dest = 9; /* NULL */
       else
          exp->dest = V_008DFC_SQ_EXP_POS;
-      /* insert the null export 1 instruction before endpgm */
+      /* insert the null export 1 instruction before branch/endpgm */
       block.instructions.insert(block.instructions.end() - 1, std::move(exp));
    }
 }
diff --git a/src/amd/compiler/aco_instruction_selection.cpp b/src/amd/compiler/aco_instruction_selection.cpp
index c3e9cf9f913..4d464cc935e 100644
--- a/src/amd/compiler/aco_instruction_selection.cpp
+++ b/src/amd/compiler/aco_instruction_selection.cpp
@@ -8874,7 +8874,7 @@ void select_program(Program *program,
    program->config->float_mode = program->blocks[0].fp_mode.val;
 
    append_logical_end(ctx.block);
-   ctx.block->kind |= block_kind_uniform;
+   ctx.block->kind |= block_kind_uniform | block_kind_export_end;
    Builder bld(ctx.program, ctx.block);
    if (ctx.program->wb_smem_l1_on_end)
       bld.smem(aco_opcode::s_dcache_wb, false);
diff --git a/src/amd/compiler/aco_ir.h b/src/amd/compiler/aco_ir.h
index 24d1acf2b79..d3ebecc081e 100644
--- a/src/amd/compiler/aco_ir.h
+++ b/src/amd/compiler/aco_ir.h
@@ -1002,6 +1002,7 @@ enum block_kind {
    block_kind_uses_discard_if = 1 << 12,
    block_kind_needs_lowering = 1 << 13,
    block_kind_uses_demote = 1 << 14,
+   block_kind_export_end = 1 << 15,
 };