[Mesa-dev] [PATCH] r600g: Disable LLVM by default at runtime for graphics

[Michel Dänzer]

From: Michel Dänzer <michel.daenzer at amd.com>

For graphics, the LLVM compiler backend currently has many shortcomings
compared to the non-LLVM one. E.g. it can't handle geometry shaders yet,
but that's just the tip of the iceberg.

So building Mesa with --enable-r600-llvm-compiler is currently not
recommended for anyone who doesn't want to work on fixing those issues.
However, for protection of users who end up enabling it anyway for some
reason, let's disable the LLVM backend at runtime by default. It can be
enabled with the environment variable R600_DEBUG=llvm.

Cc: "10.1" <mesa-stable at lists.freedesktop.org>
Signed-off-by: Michel Dänzer <michel.daenzer at amd.com>
---
 src/gallium/drivers/r600/r600_pipe.c   | 6 +++---
 src/gallium/drivers/r600/r600_pipe.h   | 2 +-
 src/gallium/drivers/r600/r600_shader.c | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/gallium/drivers/r600/r600_pipe.c b/src/gallium/drivers/r600/r600_pipe.c
index c037662..7d254a9 100644
--- a/src/gallium/drivers/r600/r600_pipe.c
+++ b/src/gallium/drivers/r600/r600_pipe.c
@@ -45,7 +45,7 @@
 static const struct debug_named_value r600_debug_options[] = {
 	/* features */
 #if defined(R600_USE_LLVM)
-	{ "nollvm", DBG_NO_LLVM, "Disable the LLVM shader compiler" },
+	{ "llvm", DBG_LLVM, "Enable the LLVM shader compiler" },
 #endif
 	{ "nocpdma", DBG_NO_CP_DMA, "Disable CP DMA" },
 
@@ -569,8 +569,8 @@ struct pipe_screen *r600_screen_create(struct radeon_winsys *ws)
 		rscreen->b.debug_flags |= DBG_FS | DBG_VS | DBG_GS | DBG_PS | DBG_CS;
 	if (debug_get_bool_option("R600_HYPERZ", FALSE))
 		rscreen->b.debug_flags |= DBG_HYPERZ;
-	if (!debug_get_bool_option("R600_LLVM", TRUE))
-		rscreen->b.debug_flags |= DBG_NO_LLVM;
+	if (debug_get_bool_option("R600_LLVM", FALSE))
+		rscreen->b.debug_flags |= DBG_LLVM;
 
 	if (rscreen->b.family == CHIP_UNKNOWN) {
 		fprintf(stderr, "r600: Unknown chipset 0x%04X\n", rscreen->b.info.pci_id);
diff --git a/src/gallium/drivers/r600/r600_pipe.h b/src/gallium/drivers/r600/r600_pipe.h
index 0a3fa42..6787d98 100644
--- a/src/gallium/drivers/r600/r600_pipe.h
+++ b/src/gallium/drivers/r600/r600_pipe.h
@@ -195,7 +195,7 @@ struct r600_gs_rings_state {
 
 /* This must start from 16. */
 /* features */
-#define DBG_NO_LLVM		(1 << 17)
+#define DBG_LLVM		(1 << 17)
 #define DBG_NO_CP_DMA		(1 << 18)
 /* shader backend */
 #define DBG_NO_SB		(1 << 21)
diff --git a/src/gallium/drivers/r600/r600_shader.c b/src/gallium/drivers/r600/r600_shader.c
index b4b357e..81d879a 100644
--- a/src/gallium/drivers/r600/r600_shader.c
+++ b/src/gallium/drivers/r600/r600_shader.c
@@ -1538,7 +1538,7 @@ static int r600_shader_from_tgsi(struct r600_context *rctx,
 	bool pos_emitted = false;
 
 #ifdef R600_USE_LLVM
-	use_llvm = !(rscreen->b.debug_flags & DBG_NO_LLVM);
+	use_llvm = rscreen->b.debug_flags & DBG_LLVM;
 #endif
 	ctx.bc = &shader->bc;
 	ctx.shader = shader;
-- 
1.9.0