efi_loader: Optimize GOP switch

We usually try to compile for size, not for speed. Unfortunately with the
more powerful GOP infrastructure to handle all sorts of GOP operations, we
end up slowing down our copying hot path quite a lot.

So this patch moves the 4 possible GOP operation modes into separate
functions which call a common function again. The end result of that is
more optimized code that can properly do constant propagation throughout
its switch() statements and thus removes compares in the hot path.

Signed-off-by: Alexander Graf <agraf@suse.de>

lib/efi_loader/efi_gop.c

@@ -77,42 +77,24 @@ static __always_inline u16 efi_blt_col_to_vid16(struct efi_gop_pixel *blt)
 	       (u16)(blt->blue  >> 3);
 }
 
-/*
- * Copy rectangle.
- *
- * This function implements the Blt service of the EFI_GRAPHICS_OUTPUT_PROTOCOL.
- * See the Unified Extensible Firmware Interface (UEFI) specification for
- * details.
- *
- * @this:	EFI_GRAPHICS_OUTPUT_PROTOCOL
- * @buffer:	pixel buffer
- * @sx:		source x-coordinate
- * @sy:		source y-coordinate
- * @dx:		destination x-coordinate
- * @dy:		destination y-coordinate
- * @width:	width of rectangle
- * @height:	height of rectangle
- * @delta:	length in bytes of a line in the pixel buffer (optional)
- * @return:	status code
- */
-efi_status_t EFIAPI gop_blt(struct efi_gop *this, struct efi_gop_pixel *buffer,
+static __always_inline efi_status_t gop_blt_int(struct efi_gop *this,
+						struct efi_gop_pixel *buffer,
 						u32 operation, efi_uintn_t sx,
 						efi_uintn_t sy, efi_uintn_t dx,
-			    efi_uintn_t dy, efi_uintn_t width,
-			    efi_uintn_t height, efi_uintn_t delta)
+						efi_uintn_t dy,
+						efi_uintn_t width,
+						efi_uintn_t height,
+						efi_uintn_t delta)
 {
 	struct efi_gop_obj *gopobj = container_of(this, struct efi_gop_obj, ops);
 	efi_uintn_t i, j, linelen;
 	u32 *fb32 = gopobj->fb;
 	u16 *fb16 = gopobj->fb;
 
-	EFI_ENTRY("%p, %p, %u, %zu, %zu, %zu, %zu, %zu, %zu, %zu", this,
-		  buffer, operation, sx, sy, dx, dy, width, height, delta);
-
 	if (delta) {
 		/* Check for 4 byte alignment */
 		if (delta & 3)
-			return EFI_EXIT(EFI_INVALID_PARAMETER);
+			return EFI_INVALID_PARAMETER;
 		linelen = delta >> 2;
 	} else {
 		linelen = width;
@@ -124,16 +106,16 @@ efi_status_t EFIAPI gop_blt(struct efi_gop *this, struct efi_gop_pixel *buffer,
 		break;
 	case EFI_BLT_BUFFER_TO_VIDEO:
 		if (sx + width > linelen)
-			return EFI_EXIT(EFI_INVALID_PARAMETER);
+			return EFI_INVALID_PARAMETER;
 		break;
 	case EFI_BLT_VIDEO_TO_BLT_BUFFER:
 	case EFI_BLT_VIDEO_TO_VIDEO:
 		if (sx + width > gopobj->info.width ||
 		    sy + height > gopobj->info.height)
-			return EFI_EXIT(EFI_INVALID_PARAMETER);
+			return EFI_INVALID_PARAMETER;
 		break;
 	default:
-		return EFI_EXIT(EFI_INVALID_PARAMETER);
+		return EFI_INVALID_PARAMETER;
 	}
 
 	/* Check destination rectangle */
@@ -143,11 +125,11 @@ efi_status_t EFIAPI gop_blt(struct efi_gop *this, struct efi_gop_pixel *buffer,
 	case EFI_BLT_VIDEO_TO_VIDEO:
 		if (dx + width > gopobj->info.width ||
 		    dy + height > gopobj->info.height)
-			return EFI_EXIT(EFI_INVALID_PARAMETER);
+			return EFI_INVALID_PARAMETER;
 		break;
 	case EFI_BLT_VIDEO_TO_BLT_BUFFER:
 		if (dx + width > linelen)
-			return EFI_EXIT(EFI_INVALID_PARAMETER);
+			return EFI_INVALID_PARAMETER;
 		break;
 	}
 
@@ -185,7 +167,7 @@ efi_status_t EFIAPI gop_blt(struct efi_gop *this, struct efi_gop_pixel *buffer,
 						(i + sy) + j + sx]);
 					break;
 				default:
-					return EFI_EXIT(EFI_UNSUPPORTED);
+					return EFI_UNSUPPORTED;
 				}
 				break;
 			}
@@ -217,13 +199,123 @@ efi_status_t EFIAPI gop_blt(struct efi_gop *this, struct efi_gop_pixel *buffer,
 						efi_blt_col_to_vid16(&pix);
 					break;
 				default:
-					return EFI_EXIT(EFI_UNSUPPORTED);
+					return EFI_UNSUPPORTED;
 				}
 				break;
 			}
 		}
 	}
 
+	return EFI_SUCCESS;
+}
+
+/*
+ * Gcc can't optimize our BLT function well, but we need to make sure that
+ * our 2-dimensional loop gets executed very quickly, otherwise the system
+ * will feel slow.
+ *
+ * By manually putting all obvious branch targets into functions which call
+ * our generic blt function with constants, the compiler can successfully
+ * optimize for speed.
+ */
+static efi_status_t gop_blt_video_fill(struct efi_gop *this,
+				       struct efi_gop_pixel *buffer,
+				       u32 foo, efi_uintn_t sx,
+				       efi_uintn_t sy, efi_uintn_t dx,
+				       efi_uintn_t dy, efi_uintn_t width,
+				       efi_uintn_t height, efi_uintn_t delta)
+{
+	return gop_blt_int(this, buffer, EFI_BLT_VIDEO_FILL, sx, sy, dx,
+			   dy, width, height, delta);
+}
+
+static efi_status_t gop_blt_buf_to_vid(struct efi_gop *this,
+				       struct efi_gop_pixel *buffer,
+				       u32 foo, efi_uintn_t sx,
+				       efi_uintn_t sy, efi_uintn_t dx,
+				       efi_uintn_t dy, efi_uintn_t width,
+				       efi_uintn_t height, efi_uintn_t delta)
+{
+	return gop_blt_int(this, buffer, EFI_BLT_BUFFER_TO_VIDEO, sx, sy, dx,
+			   dy, width, height, delta);
+}
+
+static efi_status_t gop_blt_vid_to_vid(struct efi_gop *this,
+				       struct efi_gop_pixel *buffer,
+				       u32 foo, efi_uintn_t sx,
+				       efi_uintn_t sy, efi_uintn_t dx,
+				       efi_uintn_t dy, efi_uintn_t width,
+				       efi_uintn_t height, efi_uintn_t delta)
+{
+	return gop_blt_int(this, buffer, EFI_BLT_VIDEO_TO_VIDEO, sx, sy, dx,
+			   dy, width, height, delta);
+}
+
+static efi_status_t gop_blt_vid_to_buf(struct efi_gop *this,
+				       struct efi_gop_pixel *buffer,
+				       u32 foo, efi_uintn_t sx,
+				       efi_uintn_t sy, efi_uintn_t dx,
+				       efi_uintn_t dy, efi_uintn_t width,
+				       efi_uintn_t height, efi_uintn_t delta)
+{
+	return gop_blt_int(this, buffer, EFI_BLT_VIDEO_TO_BLT_BUFFER, sx, sy,
+			   dx, dy, width, height, delta);
+}
+
+/*
+ * Copy rectangle.
+ *
+ * This function implements the Blt service of the EFI_GRAPHICS_OUTPUT_PROTOCOL.
+ * See the Unified Extensible Firmware Interface (UEFI) specification for
+ * details.
+ *
+ * @this:	EFI_GRAPHICS_OUTPUT_PROTOCOL
+ * @buffer:	pixel buffer
+ * @sx:		source x-coordinate
+ * @sy:		source y-coordinate
+ * @dx:		destination x-coordinate
+ * @dy:		destination y-coordinate
+ * @width:	width of rectangle
+ * @height:	height of rectangle
+ * @delta:	length in bytes of a line in the pixel buffer (optional)
+ * @return:	status code
+ */
+efi_status_t EFIAPI gop_blt(struct efi_gop *this, struct efi_gop_pixel *buffer,
+			    u32 operation, efi_uintn_t sx,
+			    efi_uintn_t sy, efi_uintn_t dx,
+			    efi_uintn_t dy, efi_uintn_t width,
+			    efi_uintn_t height, efi_uintn_t delta)
+{
+	efi_status_t ret = EFI_INVALID_PARAMETER;
+
+	EFI_ENTRY("%p, %p, %u, %zu, %zu, %zu, %zu, %zu, %zu, %zu", this,
+		  buffer, operation, sx, sy, dx, dy, width, height, delta);
+
+	/* Allow for compiler optimization */
+	switch (operation) {
+	case EFI_BLT_VIDEO_FILL:
+		ret = gop_blt_video_fill(this, buffer, operation, sx, sy, dx,
+					 dy, width, height, delta);
+		break;
+	case EFI_BLT_BUFFER_TO_VIDEO:
+		ret = gop_blt_buf_to_vid(this, buffer, operation, sx, sy, dx,
+					 dy, width, height, delta);
+		break;
+	case EFI_BLT_VIDEO_TO_VIDEO:
+		ret = gop_blt_vid_to_vid(this, buffer, operation, sx, sy, dx,
+					 dy, width, height, delta);
+		break;
+	case EFI_BLT_VIDEO_TO_BLT_BUFFER:
+		ret = gop_blt_vid_to_buf(this, buffer, operation, sx, sy, dx,
+					 dy, width, height, delta);
+		break;
+	default:
+		ret = EFI_UNSUPPORTED;
+	}
+
+	if (ret != EFI_SUCCESS)
+		return EFI_EXIT(ret);
+
 #ifdef CONFIG_DM_VIDEO
 	video_sync_all();
 #else