gallium/radeon: cleanup and fix branch emits

Some of the existing code is needlessly complicated. The basic principle
should be: control-flow opcodes emit branches to properly terminate the
current block, _unless_ the current block already has a terminator (which
happens if and only if there was a BRK or CONT).

This also fixes a bug where multiple terminators were created in a block.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97887
Cc: mesa-stable@lists.freedesktop.org
Reviewed-by: Marek Olšák <marek.olsak@amd.com>

diff --git a/src/gallium/drivers/radeon/radeon_setup_tgsi_llvm.c b/src/gallium/drivers/radeon/radeon_setup_tgsi_llvm.c
index bcb3143319d3d2be342fa04dbf80678fb4871a3e..201bed88707ed1836ac62cdffa304c10a0bb333c 100644 (file)
--- a/src/gallium/drivers/radeon/radeon_setup_tgsi_llvm.c
+++ b/src/gallium/drivers/radeon/radeon_setup_tgsi_llvm.c
@@ -796,6 +796,16 @@ void radeon_llvm_emit_store(struct lp_build_tgsi_context *bld_base,
        }
 }
 
+/* Emit a branch to the given default target for the current block if
+ * applicable -- that is, if the current block does not already contain a
+ * branch from a break or continue.
+ */
+static void emit_default_branch(LLVMBuilderRef builder, LLVMBasicBlockRef target)
+{
+       if (!LLVMGetBasicBlockTerminator(LLVMGetInsertBlock(builder)))
+                LLVMBuildBr(builder, target);
+}
+
 static void bgnloop_emit(const struct lp_build_tgsi_action *action,
                         struct lp_build_tgsi_context *bld_base,
                         struct lp_build_emit_data *emit_data)
@@ -856,28 +866,8 @@ static void else_emit(const struct lp_build_tgsi_action *action,
        struct radeon_llvm_context *ctx = radeon_llvm_context(bld_base);
        struct gallivm_state *gallivm = bld_base->base.gallivm;
        struct radeon_llvm_branch *current_branch = get_current_branch(ctx);
-       LLVMBasicBlockRef current_block = LLVMGetInsertBlock(gallivm->builder);
-
-       /* We need to add a terminator to the current block if the previous
-        * instruction was an ENDIF.Example:
-        * IF
-        *   [code]
-        *   IF
-        *     [code]
-        *   ELSE
-        *    [code]
-        *   ENDIF <--
-        * ELSE<--
-        *   [code]
-        * ENDIF
-        */
 
-       if (current_block != current_branch->if_block) {
-               LLVMBuildBr(gallivm->builder, current_branch->endif_block);
-       }
-       if (!LLVMGetBasicBlockTerminator(current_branch->if_block)) {
-               LLVMBuildBr(gallivm->builder, current_branch->endif_block);
-       }
+       emit_default_branch(gallivm->builder, current_branch->endif_block);
        current_branch->has_else = 1;
        LLVMPositionBuilderAtEnd(gallivm->builder, current_branch->else_block);
 }
@@ -889,26 +879,15 @@ static void endif_emit(const struct lp_build_tgsi_action *action,
        struct radeon_llvm_context *ctx = radeon_llvm_context(bld_base);
        struct gallivm_state *gallivm = bld_base->base.gallivm;
        struct radeon_llvm_branch *current_branch = get_current_branch(ctx);
-       LLVMBasicBlockRef current_block = LLVMGetInsertBlock(gallivm->builder);
 
-       /* If we have consecutive ENDIF instructions, then the first ENDIF
-        * will not have a terminator, so we need to add one. */
-       if (current_block != current_branch->if_block
-                       && current_block != current_branch->else_block
-                       && !LLVMGetBasicBlockTerminator(current_block)) {
+       emit_default_branch(gallivm->builder, current_branch->endif_block);
 
-                LLVMBuildBr(gallivm->builder, current_branch->endif_block);
-       }
+       /* Need to fixup an empty else block if there was no ELSE opcode. */
        if (!LLVMGetBasicBlockTerminator(current_branch->else_block)) {
                LLVMPositionBuilderAtEnd(gallivm->builder, current_branch->else_block);
                LLVMBuildBr(gallivm->builder, current_branch->endif_block);
        }
 
-       if (!LLVMGetBasicBlockTerminator(current_branch->if_block)) {
-               LLVMPositionBuilderAtEnd(gallivm->builder, current_branch->if_block);
-               LLVMBuildBr(gallivm->builder, current_branch->endif_block);
-       }
-
        LLVMPositionBuilderAtEnd(gallivm->builder, current_branch->endif_block);
        ctx->branch_depth--;
 }
@@ -921,9 +900,7 @@ static void endloop_emit(const struct lp_build_tgsi_action *action,
        struct gallivm_state *gallivm = bld_base->base.gallivm;
        struct radeon_llvm_loop *current_loop = get_current_loop(ctx);
 
-       if (!LLVMGetBasicBlockTerminator(LLVMGetInsertBlock(gallivm->builder))) {
-                LLVMBuildBr(gallivm->builder, current_loop->loop_block);
-       }
+       emit_default_branch(gallivm->builder, current_loop->loop_block);
 
        LLVMPositionBuilderAtEnd(gallivm->builder, current_loop->endloop_block);
        ctx->loop_depth--;