radeonsi: move emit_optimization_barrier() to ac

Reviewed-by: Nicolai Hähnle <[email protected]>
Reviewed-by: Marek Olšák <[email protected]>
Signed-off-by: Dave Airlie <[email protected]>

2 files changed, 45 insertions, 0 deletions

diff --git a/src/amd/common/ac_llvm_build.c b/src/amd/common/ac_llvm_build.c
index 2503608e26b..9045df7a0d9 100644
--- a/src/amd/common/ac_llvm_build.c
+++ b/src/amd/common/ac_llvm_build.c
@@ -36,6 +36,7 @@
 #include "ac_exp_param.h"
 #include "util/bitscan.h"
 #include "util/macros.h"
+#include "util/u_atomic.h"
 #include "sid.h"
 
 #include "shader_enums.h"
@@ -200,6 +201,48 @@ void ac_build_type_name_for_intr(LLVMTypeRef type, char *buf, unsigned bufsize)
 	}
 }
 
+/* Prevent optimizations (at least of memory accesses) across the current
+ * point in the program by emitting empty inline assembly that is marked as
+ * having side effects.
+ *
+ * Optionally, a value can be passed through the inline assembly to prevent
+ * LLVM from hoisting calls to ReadNone functions.
+ */
+void
+ac_build_optimization_barrier(struct ac_llvm_context *ctx,
+			      LLVMValueRef *pvgpr)
+{
+	static int counter = 0;
+
+	LLVMBuilderRef builder = ctx->builder;
+	char code[16];
+
+	snprintf(code, sizeof(code), "; %d", p_atomic_inc_return(&counter));
+
+	if (!pvgpr) {
+		LLVMTypeRef ftype = LLVMFunctionType(ctx->voidt, NULL, 0, false);
+		LLVMValueRef inlineasm = LLVMConstInlineAsm(ftype, code, "", true, false);
+		LLVMBuildCall(builder, inlineasm, NULL, 0, "");
+	} else {
+		LLVMTypeRef ftype = LLVMFunctionType(ctx->i32, &ctx->i32, 1, false);
+		LLVMValueRef inlineasm = LLVMConstInlineAsm(ftype, code, "=v,0", true, false);
+		LLVMValueRef vgpr = *pvgpr;
+		LLVMTypeRef vgpr_type = LLVMTypeOf(vgpr);
+		unsigned vgpr_size = ac_get_type_size(vgpr_type);
+		LLVMValueRef vgpr0;
+
+		assert(vgpr_size % 4 == 0);
+
+		vgpr = LLVMBuildBitCast(builder, vgpr, LLVMVectorType(ctx->i32, vgpr_size / 4), "");
+		vgpr0 = LLVMBuildExtractElement(builder, vgpr, ctx->i32_0, "");
+		vgpr0 = LLVMBuildCall(builder, inlineasm, &vgpr0, 1, "");
+		vgpr = LLVMBuildInsertElement(builder, vgpr, vgpr0, ctx->i32_0, "");
+		vgpr = LLVMBuildBitCast(builder, vgpr, vgpr_type, "");
+
+		*pvgpr = vgpr;
+	}
+}
+
 LLVMValueRef
 ac_build_gather_values_extended(struct ac_llvm_context *ctx,
 				LLVMValueRef *values,
diff --git a/src/amd/common/ac_llvm_build.h b/src/amd/common/ac_llvm_build.h
index cbc938d5a0a..4466e2f3057 100644
--- a/src/amd/common/ac_llvm_build.h
+++ b/src/amd/common/ac_llvm_build.h
@@ -75,6 +75,8 @@ ac_build_intrinsic(struct ac_llvm_context *ctx, const char *name,
 
 void ac_build_type_name_for_intr(LLVMTypeRef type, char *buf, unsigned bufsize);
 
+void ac_build_optimization_barrier(struct ac_llvm_context *ctx,
+				   LLVMValueRef *pvgpr);
 LLVMValueRef
 ac_build_gather_values_extended(struct ac_llvm_context *ctx,
 				LLVMValueRef *values,