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authorRoland Scheidegger <sroland@vmware.com>2013-03-16 02:55:43 +0100
committerRoland Scheidegger <sroland@vmware.com>2013-03-19 18:04:05 +0100
commit5af7b45986d1b56c568ebe9c3a40d48853e2e9ff (patch)
tree15cf77ef3b7ed571d08c85d91f2e106309f4ffce
parentafc1b7c21f795c1bf18f1edc376624011e2dfd7c (diff)
gallivm: fix return opcode handling in main function of a shader
If we're in some conditional or loop we must not return, or the code after the condition is never executed. (v2): And, we also can't just continue as nothing happened, since the mask update code would later check if we actually have a mask, so we need to remember that there was a return in main where we didn't exit (to illustrate this, a ret in a if clause would cause a mask update which is still ok as we're in a conditional, but after the endif the mask update code would drop the mask hence bringing execution back to pixels which should have their execution mask set to zero by the ret). Thanks to Christoph Bumiller for figuring this out. This fixes https://bugs.freedesktop.org/show_bug.cgi?id=62357. Note: This is a candidate for the stable branches. Reviewed-by: Jose Fonseca <jfonseca@vmware.com>
-rw-r--r--src/gallium/auxiliary/gallivm/lp_bld_tgsi.h1
-rw-r--r--src/gallium/auxiliary/gallivm/lp_bld_tgsi_soa.c20
2 files changed, 18 insertions, 3 deletions
diff --git a/src/gallium/auxiliary/gallivm/lp_bld_tgsi.h b/src/gallium/auxiliary/gallivm/lp_bld_tgsi.h
index dac97c35a9..6e65e126d6 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_tgsi.h
+++ b/src/gallium/auxiliary/gallivm/lp_bld_tgsi.h
@@ -243,6 +243,7 @@ struct lp_exec_mask {
struct lp_build_context *bld;
boolean has_mask;
+ boolean ret_in_main;
LLVMTypeRef int_vec_type;
diff --git a/src/gallium/auxiliary/gallivm/lp_bld_tgsi_soa.c b/src/gallium/auxiliary/gallivm/lp_bld_tgsi_soa.c
index f157dc11d2..cafc61f60f 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_tgsi_soa.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_tgsi_soa.c
@@ -73,6 +73,7 @@ static void lp_exec_mask_init(struct lp_exec_mask *mask, struct lp_build_context
mask->bld = bld;
mask->has_mask = FALSE;
+ mask->ret_in_main = FALSE;
mask->cond_stack_size = 0;
mask->loop_stack_size = 0;
mask->call_stack_size = 0;
@@ -108,7 +109,7 @@ static void lp_exec_mask_update(struct lp_exec_mask *mask)
} else
mask->exec_mask = mask->cond_mask;
- if (mask->call_stack_size) {
+ if (mask->call_stack_size || mask->ret_in_main) {
mask->exec_mask = LLVMBuildAnd(builder,
mask->exec_mask,
mask->ret_mask,
@@ -117,7 +118,8 @@ static void lp_exec_mask_update(struct lp_exec_mask *mask)
mask->has_mask = (mask->cond_stack_size > 0 ||
mask->loop_stack_size > 0 ||
- mask->call_stack_size > 0);
+ mask->call_stack_size > 0 ||
+ mask->ret_in_main);
}
static void lp_exec_mask_cond_push(struct lp_exec_mask *mask,
@@ -348,11 +350,23 @@ static void lp_exec_mask_ret(struct lp_exec_mask *mask, int *pc)
LLVMBuilderRef builder = mask->bld->gallivm->builder;
LLVMValueRef exec_mask;
- if (mask->call_stack_size == 0) {
+ if (mask->cond_stack_size == 0 &&
+ mask->loop_stack_size == 0 &&
+ mask->call_stack_size == 0) {
/* returning from main() */
*pc = -1;
return;
}
+
+ if (mask->call_stack_size == 0) {
+ /*
+ * This requires special handling since we need to ensure
+ * we don't drop the mask even if we have no call stack
+ * (e.g. after a ret in a if clause after the endif)
+ */
+ mask->ret_in_main = TRUE;
+ }
+
exec_mask = LLVMBuildNot(builder,
mask->exec_mask,
"ret");