ac/nir: Fix store_scratch with a non-full writemask

By adding one more helper to ac_llvm_build, we can also easily keep
vector stores together.

Fixes the
tests/spec/glsl-1.30/execution/fs-large-local-array-vec4.shader_test
piglit test.

Fixes: 74470baebb ("ac/nir: Lower large indirect variables to scratch")
Reviewed-by: Marek Olšák <marek.olsak@amd.com

src/amd/common/ac_llvm_build.c

@@ -626,6 +626,22 @@ ac_build_expand(struct ac_llvm_context *ctx,
 	return ac_build_gather_values(ctx, chan, dst_channels);
 }
 
+/* Extract components [start, start + channels) from a vector.
+ */
+LLVMValueRef
+ac_extract_components(struct ac_llvm_context *ctx,
+		      LLVMValueRef value,
+		      unsigned start,
+		      unsigned channels)
+{
+	LLVMValueRef chan[channels];
+
+	for (unsigned i = 0; i < channels; i++)
+		chan[i] = ac_llvm_extract_elem(ctx, value, i + start);
+
+	return ac_build_gather_values(ctx, chan, channels);
+}
+
 /* Expand a scalar or vector to <4 x type> by filling the remaining channels
  * with undef. Extract at most num_channels components from the input.
  */

src/amd/common/ac_llvm_build.h

@@ -190,6 +190,13 @@ LLVMValueRef
 ac_build_gather_values(struct ac_llvm_context *ctx,
 		       LLVMValueRef *values,
 		       unsigned value_count);
+
+LLVMValueRef
+ac_extract_components(struct ac_llvm_context *ctx,
+		      LLVMValueRef value,
+		      unsigned start,
+		      unsigned channels);
+
 LLVMValueRef ac_build_expand_to_vec4(struct ac_llvm_context *ctx,
 				     LLVMValueRef value,
 				     unsigned num_channels);

src/amd/common/ac_nir_to_llvm.c

@@ -3637,13 +3637,27 @@ static void visit_intrinsic(struct ac_nir_context *ctx,
 						 offset);
 		LLVMTypeRef comp_type =
 			LLVMIntTypeInContext(ctx->ac.context, instr->src[0].ssa->bit_size);
-		LLVMTypeRef vec_type =
-			instr->src[0].ssa->num_components == 1 ? comp_type :
-			LLVMVectorType(comp_type, instr->src[0].ssa->num_components);
 		unsigned addr_space = LLVMGetPointerAddressSpace(LLVMTypeOf(ptr));
 		ptr = LLVMBuildBitCast(ctx->ac.builder, ptr,
-				       LLVMPointerType(vec_type, addr_space), "");
+				       LLVMPointerType(comp_type, addr_space), "");
-		LLVMBuildStore(ctx->ac.builder, get_src(ctx, instr->src[0]), ptr);
+		LLVMValueRef src = get_src(ctx, instr->src[0]);
+		unsigned wrmask = nir_intrinsic_write_mask(instr);
+		while (wrmask) {
+			int start, count;
+			u_bit_scan_consecutive_range(&wrmask, &start, &count);
+			
+			LLVMValueRef offset = LLVMConstInt(ctx->ac.i32, start, false);
+			LLVMValueRef offset_ptr = LLVMBuildGEP(ctx->ac.builder, ptr, &offset, 1, "");
+			LLVMTypeRef vec_type =
+				count == 1 ? comp_type : LLVMVectorType(comp_type, count);
+			offset_ptr = LLVMBuildBitCast(ctx->ac.builder,
+						      offset_ptr,
+						      LLVMPointerType(vec_type, addr_space),
+						      "");
+			LLVMValueRef offset_src =
+				ac_extract_components(&ctx->ac, src, start, count);
+			LLVMBuildStore(ctx->ac.builder, offset_src, offset_ptr);
+		}
 		break;
 	}
 	default: