ac/llvm: insert phis before demote kill

LLVM (like NIR) requires phi instructions to be before any other
instructions in the block. ac_branch_exited() can insert non-phi
instructions before visit_block() adds phis, so visit_block() should add
phi instructions before the non-phi instructions ac_branch_exited()
inserts.

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Fixes: aa757f4f8c3 ("ac/llvm: fix demote inside conditional branches")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8054>

diff --git a/src/amd/llvm/ac_nir_to_llvm.c b/src/amd/llvm/ac_nir_to_llvm.c
index 29c804f955bcfa8580b3c7fd70fa6d1e9e5c8767..19de5c4ece4dca6a0191865e09c7f98202e3dd3f 100644 (file)
--- a/src/amd/llvm/ac_nir_to_llvm.c
+++ b/src/amd/llvm/ac_nir_to_llvm.c
@@ -4727,6 +4727,21 @@ static void visit_cf_list(struct ac_nir_context *ctx, struct exec_list *list);
 
 static void visit_block(struct ac_nir_context *ctx, nir_block *block)
 {
+   LLVMBasicBlockRef blockref = LLVMGetInsertBlock(ctx->ac.builder);
+   LLVMValueRef first = LLVMGetFirstInstruction(blockref);
+   if (first) {
+      /* ac_branch_exited() might have already inserted non-phis */
+      LLVMPositionBuilderBefore(ctx->ac.builder, LLVMGetFirstInstruction(blockref));
+   }
+
+   nir_foreach_instr(instr, block) {
+      if (instr->type != nir_instr_type_phi)
+         break;
+      visit_phi(ctx, nir_instr_as_phi(instr));
+   }
+
+   LLVMPositionBuilderAtEnd(ctx->ac.builder, blockref);
+
    nir_foreach_instr (instr, block) {
       switch (instr->type) {
       case nir_instr_type_alu:
@@ -4742,7 +4757,6 @@ static void visit_block(struct ac_nir_context *ctx, nir_block *block)
          visit_tex(ctx, nir_instr_as_tex(instr));
          break;
       case nir_instr_type_phi:
-         visit_phi(ctx, nir_instr_as_phi(instr));
          break;
       case nir_instr_type_ssa_undef:
          visit_ssa_undef(ctx, nir_instr_as_ssa_undef(instr));