Bug 1942738 - Move the .fpu neon directive around. r=gfx-reviewers,lsalzman

clang's integrated assembler doesn't handle .fpu coming before .arch
like GNU as does.

The pixman patch was sent upstream: https://gitlab.freedesktop.org/pixman/pixman/-/issues/113#note_2746582

Differential Revision: https://phabricator.services.mozilla.com/D235087

gfx/cairo/README

@@ -63,3 +63,5 @@ pixman-interp.patch: use lower quality interpolation by default on mobile
 pixman-intrin.patch: include intrin.h on Windows to fix bustage
 
 pixman-rename.patch: include pixman-rename.h for renaming of external symbols
+
+pixman-neon.patch: fix for a build failure with clang on armhf linux

gfx/cairo/libpixman/src/pixman-arm-neon-asm-bilinear.S

@@ -55,9 +55,9 @@
 #endif
 
 .text
-.fpu neon
 .arch armv7a
 .object_arch armv4
+.fpu neon
 .eabi_attribute 10, 0
 .eabi_attribute 12, 0
 .arm

gfx/cairo/libpixman/src/pixman-arm-neon-asm.S

@@ -40,9 +40,9 @@
 #endif
 
     .text
-    .fpu neon
     .arch armv7a
     .object_arch armv4
+    .fpu neon
     .eabi_attribute 10, 0 /* suppress Tag_FP_arch */
     .eabi_attribute 12, 0 /* suppress Tag_Advanced_SIMD_arch */
     .arm

gfx/cairo/pixman-neon.patch

@@ -0,0 +1,30 @@
+diff --git a/gfx/cairo/libpixman/src/pixman-arm-neon-asm-bilinear.S b/gfx/cairo/libpixman/src/pixman-arm-neon-asm-bilinear.S
+index 6bd27360aa027..cd33babca1e0c 100644
+--- a/gfx/cairo/libpixman/src/pixman-arm-neon-asm-bilinear.S
++++ b/gfx/cairo/libpixman/src/pixman-arm-neon-asm-bilinear.S
+@@ -55,9 +55,9 @@
+ #endif
+ 
+ .text
+-.fpu neon
+ .arch armv7a
+ .object_arch armv4
++.fpu neon
+ .eabi_attribute 10, 0
+ .eabi_attribute 12, 0
+ .arm
+diff --git a/gfx/cairo/libpixman/src/pixman-arm-neon-asm.S b/gfx/cairo/libpixman/src/pixman-arm-neon-asm.S
+index 0e092577f1c73..c04b335d1e5bd 100644
+--- a/gfx/cairo/libpixman/src/pixman-arm-neon-asm.S
++++ b/gfx/cairo/libpixman/src/pixman-arm-neon-asm.S
+@@ -40,9 +40,9 @@
+ #endif
+ 
+     .text
+-    .fpu neon
+     .arch armv7a
+     .object_arch armv4
++    .fpu neon
+     .eabi_attribute 10, 0 /* suppress Tag_FP_arch */
+     .eabi_attribute 12, 0 /* suppress Tag_Advanced_SIMD_arch */
+     .arm

gfx/ycbcr/yuv_convert_arm.cpp

@@ -53,11 +53,11 @@ void __attribute((noinline,optimize("-fomit-frame-pointer")))
      * q13, q14, q15            - various constants (#16, #149, #204, #50, #104, #154)
      */
     asm volatile (
-".fpu neon\n"
 /* Allow to build on targets not supporting neon, and force the object file
  * target to avoid bumping the final binary target */
 ".arch armv7-a\n"
 ".object_arch armv4t\n"
+".fpu neon\n"
 ".macro convert_macroblock size\n"
 /* load up to 16 source pixels */
 	".if \\size == 16\n"