Mesa (master): ac: add ac_build_readlane without optimization barrier

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Module: Mesa
Branch: master
Commit: 0f45d4dc2b15e137346e1e3f064a24302e1c9048
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=0f45d4dc2b15e137346e1e3f064a24302e1c9048

Author: Marek Olšák <marek.olsak at amd.com>
Date:   Thu Jan  2 18:41:26 2020 -0500

ac: add ac_build_readlane without optimization barrier

Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer at amd.com>

---

 src/amd/llvm/ac_llvm_build.c | 18 ++++++++++++++----
 src/amd/llvm/ac_llvm_build.h |  3 +++
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/src/amd/llvm/ac_llvm_build.c b/src/amd/llvm/ac_llvm_build.c
index f789ff5a368..3640c7c22fa 100644
--- a/src/amd/llvm/ac_llvm_build.c
+++ b/src/amd/llvm/ac_llvm_build.c
@@ -3595,8 +3595,6 @@ _ac_build_readlane(struct ac_llvm_context *ctx, LLVMValueRef src, LLVMValueRef l
 	LLVMTypeRef type = LLVMTypeOf(src);
 	LLVMValueRef result;
 
-	ac_build_optimization_barrier(ctx, &src);
-
 	src = LLVMBuildZExt(ctx->builder, src, ctx->i32, "");
 	if (lane)
 		lane = LLVMBuildZExt(ctx->builder, lane, ctx->i32, "");
@@ -3613,13 +3611,17 @@ _ac_build_readlane(struct ac_llvm_context *ctx, LLVMValueRef src, LLVMValueRef l
 
 /**
  * Builds the "llvm.amdgcn.readlane" or "llvm.amdgcn.readfirstlane" intrinsic.
+ *
+ * The optimization barrier is not needed if the value is the same in all lanes
+ * or if this is called in the outermost block.
+ *
  * @param ctx
  * @param src
  * @param lane - id of the lane or NULL for the first active lane
  * @return value of the lane
  */
-LLVMValueRef
-ac_build_readlane(struct ac_llvm_context *ctx, LLVMValueRef src, LLVMValueRef lane)
+LLVMValueRef ac_build_readlane_no_opt_barrier(struct ac_llvm_context *ctx,
+					      LLVMValueRef src, LLVMValueRef lane)
 {
 	LLVMTypeRef src_type = LLVMTypeOf(src);
 	src = ac_to_integer(ctx, src);
@@ -3648,6 +3650,14 @@ ac_build_readlane(struct ac_llvm_context *ctx, LLVMValueRef src, LLVMValueRef la
 	return LLVMBuildBitCast(ctx->builder, ret, src_type, "");
 }
 
+LLVMValueRef
+ac_build_readlane(struct ac_llvm_context *ctx, LLVMValueRef src, LLVMValueRef lane)
+{
+	ac_build_optimization_barrier(ctx, &src);
+
+	return ac_build_readlane_no_opt_barrier(ctx, src, lane);
+}
+
 LLVMValueRef
 ac_build_writelane(struct ac_llvm_context *ctx, LLVMValueRef src, LLVMValueRef value, LLVMValueRef lane)
 {
diff --git a/src/amd/llvm/ac_llvm_build.h b/src/amd/llvm/ac_llvm_build.h
index 56ec7613009..4be06a9c104 100644
--- a/src/amd/llvm/ac_llvm_build.h
+++ b/src/amd/llvm/ac_llvm_build.h
@@ -655,6 +655,9 @@ void ac_apply_fmask_to_sample(struct ac_llvm_context *ac, LLVMValueRef fmask,
 LLVMValueRef
 ac_build_ds_swizzle(struct ac_llvm_context *ctx, LLVMValueRef src, unsigned mask);
 
+LLVMValueRef ac_build_readlane_no_opt_barrier(struct ac_llvm_context *ctx,
+					      LLVMValueRef src, LLVMValueRef lane);
+
 LLVMValueRef
 ac_build_readlane(struct ac_llvm_context *ctx, LLVMValueRef src, LLVMValueRef lane);