Mesa (master): radeonsi: Set range metadata on calls to llvm.SI.tid

[Tom Stellard]

Module: Mesa
Branch: master
Commit: d3427412a335ec64d05e09e040a2ddb2b9552563
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=d3427412a335ec64d05e09e040a2ddb2b9552563

Author: Tom Stellard <thomas.stellard at amd.com>
Date:   Mon Apr 18 14:33:43 2016 -0400

radeonsi: Set range metadata on calls to llvm.SI.tid

The range metadata tells LLVM the range of expected values for this intrinsic,
so it can do some additional optimizations on the result.

Reviewed-by: Michel Dänzer <michel.daenzer at amd.com>
Reviewed-by: Marek Olšák <marek.olsak at amd.com>

---

 src/gallium/drivers/radeonsi/si_shader.c | 29 ++++++++++++++++++++++++++---
 1 file changed, 26 insertions(+), 3 deletions(-)

diff --git a/src/gallium/drivers/radeonsi/si_shader.c b/src/gallium/drivers/radeonsi/si_shader.c
index a8749e4..cd6725e 100644
--- a/src/gallium/drivers/radeonsi/si_shader.c
+++ b/src/gallium/drivers/radeonsi/si_shader.c
@@ -1116,12 +1116,35 @@ static LLVMValueRef get_sample_id(struct radeon_llvm_context *radeon_bld)
 			    SI_PARAM_ANCILLARY, 8, 4);
 }
 
+/**
+ * Set range metadata on an instruction.  This can only be used on load and
+ * call instructions.  If you know an instruction can only produce the values
+ * 0, 1, 2, you would do set_range_metadata(value, 0, 3);
+ * \p lo is the minimum value inclusive.
+ * \p hi is the maximum value exclusive.
+ */
+static void set_range_metadata(LLVMValueRef value, unsigned lo, unsigned hi)
+{
+	const char *range_md_string = "range";
+	LLVMValueRef range_md, md_args[2];
+	LLVMTypeRef type = LLVMTypeOf(value);
+	LLVMContextRef context = LLVMGetTypeContext(type);
+	unsigned md_range_id = LLVMGetMDKindIDInContext(context,
+				range_md_string, strlen(range_md_string));
+
+	md_args[0] = LLVMConstInt(type, lo, false);
+	md_args[1] = LLVMConstInt(type, hi, false);
+	range_md = LLVMMDNodeInContext(context, md_args, 2);
+	LLVMSetMetadata(value, md_range_id, range_md);
+}
+
 static LLVMValueRef get_thread_id(struct si_shader_context *ctx)
 {
 	struct gallivm_state *gallivm = &ctx->radeon_bld.gallivm;
-
-	return lp_build_intrinsic(gallivm->builder, "llvm.SI.tid", ctx->i32,
-					   NULL, 0, LLVMReadNoneAttribute);
+	LLVMValueRef tid = lp_build_intrinsic(gallivm->builder, "llvm.SI.tid",
+				ctx->i32,   NULL, 0, LLVMReadNoneAttribute);
+	set_range_metadata(tid, 0, 64);
+	return tid;
 }
 
 /**