radeonsi: add a workaround for bitfield_extract when count is 0

This ports the fix from 3d41757788ac. Both LLVM 7 & 8 continue
to have this problem.

It fixes rendering issues in some menu and loading screens of
Civ VI which can be seen in the trace from bug 104602.

Note: This does not fix the black triangles on Vega for bug
104602.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=104602
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107276

diff --git a/src/gallium/drivers/radeonsi/si_shader_tgsi_alu.c b/src/gallium/drivers/radeonsi/si_shader_tgsi_alu.c
index a768b44904798313f5922bb39d315aca88661ebb..fca2527f28d7a120d308cd88e809ff20083fc02c 100644 (file)
--- a/src/gallium/drivers/radeonsi/si_shader_tgsi_alu.c
+++ b/src/gallium/drivers/radeonsi/si_shader_tgsi_alu.c
@@ -495,18 +495,37 @@ static void emit_bfe(const struct lp_build_tgsi_action *action,
                     struct lp_build_emit_data *emit_data)
 {
        struct si_shader_context *ctx = si_shader_context(bld_base);
-       LLVMValueRef bfe_sm5;
-       LLVMValueRef cond;
-
-       bfe_sm5 = ac_build_bfe(&ctx->ac, emit_data->args[0],
-                              emit_data->args[1], emit_data->args[2],
-                              emit_data->info->opcode == TGSI_OPCODE_IBFE);
 
-       /* Correct for GLSL semantics. */
-       cond = LLVMBuildICmp(ctx->ac.builder, LLVMIntUGE, emit_data->args[2],
-                            LLVMConstInt(ctx->i32, 32, 0), "");
-       emit_data->output[emit_data->chan] =
-               LLVMBuildSelect(ctx->ac.builder, cond, emit_data->args[0], bfe_sm5, "");
+       if (HAVE_LLVM < 0x0700) {
+               LLVMValueRef bfe_sm5 =
+                       ac_build_bfe(&ctx->ac, emit_data->args[0],
+                                    emit_data->args[1], emit_data->args[2],
+                                    emit_data->info->opcode == TGSI_OPCODE_IBFE);
+
+               /* Correct for GLSL semantics. */
+               LLVMValueRef cond = LLVMBuildICmp(ctx->ac.builder, LLVMIntUGE, emit_data->args[2],
+                                                 LLVMConstInt(ctx->i32, 32, 0), "");
+               emit_data->output[emit_data->chan] =
+                       LLVMBuildSelect(ctx->ac.builder, cond, emit_data->args[0], bfe_sm5, "");
+       } else {
+               /* FIXME: LLVM 7 returns incorrect result when count is 0.
+                * https://bugs.freedesktop.org/show_bug.cgi?id=107276
+                */
+               LLVMValueRef zero = ctx->i32_0;
+               LLVMValueRef bfe_sm5 =
+                       ac_build_bfe(&ctx->ac, emit_data->args[0],
+                                    emit_data->args[1], emit_data->args[2],
+                                    emit_data->info->opcode == TGSI_OPCODE_IBFE);
+
+               /* Correct for GLSL semantics. */
+               LLVMValueRef cond = LLVMBuildICmp(ctx->ac.builder, LLVMIntUGE, emit_data->args[2],
+                                                 LLVMConstInt(ctx->i32, 32, 0), "");
+               LLVMValueRef cond2 = LLVMBuildICmp(ctx->ac.builder, LLVMIntEQ, emit_data->args[2],
+                                                  zero, "");
+               bfe_sm5 = LLVMBuildSelect(ctx->ac.builder, cond, emit_data->args[0], bfe_sm5, "");
+               emit_data->output[emit_data->chan] =
+                       LLVMBuildSelect(ctx->ac.builder, cond2, zero, bfe_sm5, "");
+       }
 }
 
 /* this is ffs in C */