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authorBrian Paul <brianp@vmware.com>2009-01-06 17:36:20 -0700
committerBrian Paul <brianp@vmware.com>2009-01-06 17:36:20 -0700
commit0b0d0dcdef2b914dceb30a8e9a80f403b0311efc (patch)
tree06bbd8cd27de59c0729e686565ab99dfbcc40d8e /src
parent1fa978c8911d00e7cac0a114110e98ebdbe4d57d (diff)
glsl: loop unroll adjustments
Add a "max complexity" heuristic to allow unrolling long loops with small bodies and short loops with large bodies. The loop unroll limits may need further tweaking...
Diffstat (limited to 'src')
-rw-r--r--src/mesa/shader/slang/slang_codegen.c21
1 files changed, 20 insertions, 1 deletions
diff --git a/src/mesa/shader/slang/slang_codegen.c b/src/mesa/shader/slang/slang_codegen.c
index 0d9674f05c4..64d72b5bfa3 100644
--- a/src/mesa/shader/slang/slang_codegen.c
+++ b/src/mesa/shader/slang/slang_codegen.c
@@ -58,11 +58,18 @@
/** Max iterations to unroll */
-const GLuint MAX_FOR_LOOP_UNROLL_ITERATIONS = 4;
+const GLuint MAX_FOR_LOOP_UNROLL_ITERATIONS = 20;
/** Max for-loop body size (in slang operations) to unroll */
const GLuint MAX_FOR_LOOP_UNROLL_BODY_SIZE = 50;
+/** Max for-loop body complexity to unroll.
+ * We'll compute complexity as the product of the number of iterations
+ * and the size of the body. So long-ish loops with very simple bodies
+ * can be unrolled, as well as short loops with larger bodies.
+ */
+const GLuint MAX_FOR_LOOP_UNROLL_COMPLEXITY = 200;
+
static slang_ir_node *
@@ -2533,6 +2540,10 @@ _slang_can_unroll_for_loop(slang_assemble_ctx * A, const slang_operation *oper)
/* get/check loop iteration limits */
start = (GLint) oper->children[0].children[0].children[1].literal[0];
end = (GLint) oper->children[1].children[0].children[1].literal[0];
+
+ if (start >= end)
+ return GL_FALSE; /* degenerate case */
+
if (end - start > MAX_FOR_LOOP_UNROLL_ITERATIONS) {
slang_info_log_print(A->log,
"Note: 'for (%s=%d; %s<%d; ++%s)' is too"
@@ -2541,6 +2552,14 @@ _slang_can_unroll_for_loop(slang_assemble_ctx * A, const slang_operation *oper)
return GL_FALSE;
}
+ if ((end - start) * bodySize > MAX_FOR_LOOP_UNROLL_COMPLEXITY) {
+ slang_info_log_print(A->log,
+ "Note: 'for (%s=%d; %s<%d; ++%s)' will generate"
+ " too much code to unroll",
+ varName, start, varName, end, varName);
+ return GL_FALSE;
+ }
+
return GL_TRUE; /* we can unroll the loop */
}