Bug 1800187 - Part 2: Refactor libpixman moz.build file. r=jfkthame

* Remove workaround for a long-fixed LLVM bug
* Remove extra flags on pixman-mmx.c
* Remove unneeded -Winline flags
* Drop SIMD exceptions for macOS
* Use correct MMX define
* Enable all SIMD optimizations for Intel builds
* Clean up platform-specific logic
* Enable aarch64 optimizations on Android & Linux

Besides removing a lot of old cruft and improving general readability, this
also re-enables MMX optimizations (the define changed upstream and wasn't
updated in moz.build to reflect that) along with unconditionally compiling
with all available Intel SIMD optimization levels. Pixman does runtime CPU
feature detection, so this should be safe. It also enables AArch64
optimizations on Android and Linux.

Depends on D161868

Differential Revision: https://phabricator.services.mozilla.com/D161869

gfx/cairo/libpixman/src/moz.build

@@ -9,26 +9,6 @@ EXPORTS += [
     'pixman.h',
 ]
 
-# Apple's arm assembler doesn't support the same syntax as
-# the standard GNU assembler, so use the C fallback paths for now.
-# This may be fixable if clang's ARM/iOS assembler improves into a
-# viable solution in the future.
-if CONFIG['OS_ARCH'] != 'Darwin' and CONFIG['CC_TYPE'] in ('clang', 'gcc'):
-    if CONFIG['HAVE_ARM_NEON']:
-        SOURCES += [
-            'pixman-arm-neon-asm-bilinear.S',
-            'pixman-arm-neon-asm.S',
-        ]
-    if CONFIG['HAVE_ARM_SIMD']:
-        SOURCES += [
-            'pixman-arm-simd-asm-scaled.S',
-            'pixman-arm-simd-asm.S',
-        ]
-    if CONFIG['CC_TYPE'] == 'clang':
-        ASFLAGS += [
-            '-no-integrated-as',
-        ]
-
 SOURCES += [
     'pixman-access-accessors.c',
     'pixman-access.c',
@@ -82,81 +62,58 @@ DEFINES['PACKAGE'] = 'mozpixman'
 
 DEFINES['_USE_MATH_DEFINES'] = True
 
-use_mmx = False
-use_sse2 = False
-use_vmx = False
-use_arm_simd_gcc = False
-use_arm_neon_gcc = False
 if CONFIG['INTEL_ARCHITECTURE']:
-    use_sse2 = True
-    if CONFIG['CPU_ARCH'] == 'x86':
-        if CONFIG['CC_TYPE'] == 'clang-cl':
-            use_mmx = True
-    if CONFIG['CC_TYPE'] in ('clang', 'gcc'):
-        use_mmx = True
+    DEFINES['USE_X86_MMX'] = True
+    DEFINES['USE_SSE2'] = True
+    DEFINES['USE_SSSE3'] = True
+    SOURCES += [
+        'pixman-mmx.c',
+        'pixman-sse2.c',
+        'pixman-ssse3.c',
+    ]
+    SOURCES['pixman-mmx.c'].flags += CONFIG['MMX_FLAGS']
+    SOURCES['pixman-sse2.c'].flags += CONFIG['SSE_FLAGS'] + CONFIG['SSE2_FLAGS']
+    SOURCES['pixman-ssse3.c'].flags += CONFIG['SSSE3_FLAGS']
+# AArch64 NEON optimizations don't build on Windows and Mac out of the box.
+elif CONFIG['CPU_ARCH'] == 'aarch64' and CONFIG['OS_TARGET'] in ('Android', 'Linux'):
+    DEFINES['USE_ARM_A64_NEON'] = True
+    SOURCES += [
+        'pixman-arm-neon.c',
+        'pixman-arma64-neon-asm-bilinear.S',
+        'pixman-arma64-neon-asm.S',
+    ]
+    SOURCES['pixman-arm-neon.c'].flags += ['-march=armv8-a']
+elif CONFIG['CPU_ARCH'] == 'arm':
+    if CONFIG['HAVE_ARM_NEON']:
+        DEFINES['USE_ARM_NEON'] = True
+        SOURCES += [
+            'pixman-arm-neon-asm-bilinear.S',
+            'pixman-arm-neon-asm.S',
+            'pixman-arm-neon.c',
+        ]
+        SOURCES['pixman-arm-neon.c'].flags += CONFIG['NEON_FLAGS']
+    if CONFIG['HAVE_ARM_SIMD']:
+        DEFINES['USE_ARM_SIMD'] = True
+        SOURCES += [
+            'pixman-arm-simd-asm-scaled.S',
+            'pixman-arm-simd-asm.S',
+            'pixman-arm-simd.c',
+        ]
 elif CONFIG['CPU_ARCH'] in ('ppc', 'ppc64'):
     if CONFIG['CC_TYPE'] in ('clang', 'gcc'):
-        use_vmx = True
-# Apple's arm assembler doesn't support the same syntax as
-# the standard GNU assembler, so use the C fallback paths for now.
-# This may be fixable if clang's ARM/iOS assembler improves into a
-# viable solution in the future.
-elif CONFIG['CPU_ARCH'] == 'arm':
-    if CONFIG['OS_ARCH'] != 'Darwin':
-        if CONFIG['HAVE_ARM_SIMD']:
-            use_arm_simd_gcc = True
-        if CONFIG['HAVE_ARM_NEON']:
-            use_arm_neon_gcc = True
+        DEFINES['USE_VMX'] = True
+        SOURCES += ['pixman-vmx.c']
+        SOURCES['pixman-vmx.c'].flags += ['-maltivec']
 
-if use_mmx:
-    DEFINES['USE_MMX'] = True
-    SOURCES += ['pixman-mmx.c']
-    SOURCES['pixman-mmx.c'].flags += CONFIG['MMX_FLAGS']
-    if CONFIG['CC_TYPE'] in ('clang', 'gcc'):
-        SOURCES['pixman-mmx.c'].flags += [
-            '-Winline',
-            '--param', 'inline-unit-growth=10000',
-            '--param', 'large-function-growth=10000',
-        ]
-
-if use_sse2:
-    DEFINES['USE_SSE'] = True
-    DEFINES['USE_SSE2'] = True
-    SOURCES += ['pixman-sse2.c']
-    SOURCES['pixman-sse2.c'].flags += CONFIG['SSE_FLAGS'] + CONFIG['SSE2_FLAGS']
-    if CONFIG['CC_TYPE'] in ('clang', 'gcc'):
-        SOURCES['pixman-sse2.c'].flags += ['-Winline']
-
-if use_vmx:
-    DEFINES['USE_VMX'] = True
-    SOURCES += ['pixman-vmx.c']
-    SOURCES['pixman-vmx.c'].flags += ['-maltivec']
-
-if use_arm_simd_gcc:
-    DEFINES['USE_ARM_SIMD'] = True
-    SOURCES += ['pixman-arm-simd.c']
-
-if use_arm_neon_gcc:
-    DEFINES['USE_ARM_NEON'] = True
-    SOURCES += ['pixman-arm-neon.c']
-    SOURCES['pixman-arm-neon.c'].flags += CONFIG['NEON_FLAGS']
-
-if CONFIG['OS_TARGET'] == 'Android' and (use_arm_neon_gcc or use_arm_simd_gcc):
-    # The assembly files in this directory are built with gas (because of
-    # -no-integrated-as), and they contain `.object_arch armv4`, which
-    # makes gas emit ARM_V4BX relocations that lld doesn't support.
-    # The code being third party and this setup being actually desirable to
-    # keep, until lld supports those relocations[1], hack around it by using
-    # the preprocessor to change it to armv7a, which is the target we use
-    # on arm android (with -march).
-    # 1. https://bugs.llvm.org/show_bug.cgi?id=38303
+if CONFIG['CC_TYPE'] == 'clang':
     ASFLAGS += [
-        '-Darmv4=armv7a'
-    ]
+        '-no-integrated-as',
+    ]    
 
 # Suppress warnings in third-party code.
 CFLAGS += [
     '-Wno-address',
+    '-Wno-braced-scalar-init',
     '-Wno-missing-field-initializers',
     '-Wno-sign-compare',
     '-Wno-incompatible-pointer-types',