The range metadata tells LLVM the range of expected values for this intrinsic,
so it can do some additional optimizations on the result.
---
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 3b6d6e9..b4f2a42 100644
--- a/src/gallium/drivers/radeonsi/si_shader.c
+++ b/src/gallium/drivers/radeonsi/si_shader.c
@@ -1114,12 +1114,35 @@ 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. To specify an instruciton 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;
}
/**
--
2.1.0
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