Use one-big-switch when [[clang::musttail]] is unavailable.
This is intended to generate the exact same code as before when
SKCMS_HAS_MUSTTAIL is not enabled.
Bug: chromium:1504816
Bug: chromium:1504823
Change-Id: Ice4e25696dfd98ba3de14bad5c58c60e69f38902
Reviewed-on: https://skia-review.googlesource.com/c/skcms/+/787502
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
diff --git a/src/Transform_inl.h b/src/Transform_inl.h
index 3920cea..1ed96bb 100644
--- a/src/Transform_inl.h
+++ b/src/Transform_inl.h
@@ -769,40 +769,60 @@
template <typename T> operator T*() { return (const T*)fArg; }
};
-// We can't declare StageFn as a function pointer which takes a pointer to StageFns; that would be
-// a circular dependency. To avoid this, StageFn is wrapped in a `struct StageList` which forward-
-// declare here.
-struct StageList;
-using StageFn = void (*)(StageList stages, const void** ctx, const char* s, char* d,
- F r, F g, F b, F a, int i);
-struct StageList {
- const StageFn* fn;
-};
+#define STAGE_PARAMS(MAYBE_REF) SKCMS_MAYBE_UNUSED const char* src, \
+ SKCMS_MAYBE_UNUSED char* dst, \
+ SKCMS_MAYBE_UNUSED F MAYBE_REF r, \
+ SKCMS_MAYBE_UNUSED F MAYBE_REF g, \
+ SKCMS_MAYBE_UNUSED F MAYBE_REF b, \
+ SKCMS_MAYBE_UNUSED F MAYBE_REF a, \
+ SKCMS_MAYBE_UNUSED int i
-#define DECLARE_STAGE(name, arg, CALL_NEXT) \
- SI void Exec_##name##_k(arg, const char* src, char* dst, F& r, F& g, F& b, F& a, int i); \
- \
- SI void Exec_##name(StageList list, const void** ctx, const char* s, char* d, \
- F r, F g, F b, F a, int i) { \
- Exec_##name##_k(Ctx{*ctx}, s, d, r, g, b, a, i); \
- ++list.fn; ++ctx; \
- CALL_NEXT; \
- } \
- \
- SI void Exec_##name##_k(arg, \
- SKCMS_MAYBE_UNUSED const char* src, \
- SKCMS_MAYBE_UNUSED char* dst, \
- SKCMS_MAYBE_UNUSED F& r, \
- SKCMS_MAYBE_UNUSED F& g, \
- SKCMS_MAYBE_UNUSED F& b, \
- SKCMS_MAYBE_UNUSED F& a, \
- SKCMS_MAYBE_UNUSED int i)
+#if SKCMS_HAS_MUSTTAIL
-#define STAGE(name, arg) \
- DECLARE_STAGE(name, arg, SKCMS_MUSTTAIL return (*list.fn)(list, ctx, s, d, r, g, b, a, i))
+ // Stages take a stage list, and each stage is responsible for tail-calling the next one.
+ //
+ // Unfortunately, we can't declare a StageFn as a function pointer which takes a pointer to
+ // another StageFn; declaring this leads to a circular dependency. To avoid this, StageFn is
+ // wrapped in a single-element `struct StageList` which we are able to forward-declare.
+ struct StageList;
+ using StageFn = void (*)(StageList stages, const void** ctx, STAGE_PARAMS());
+ struct StageList {
+ const StageFn* fn;
+ };
-#define FINAL_STAGE(name, arg) \
- DECLARE_STAGE(name, arg, /*just return to exec_stages*/)
+ #define DECLARE_STAGE(name, arg, CALL_NEXT) \
+ SI void Exec_##name##_k(arg, STAGE_PARAMS(&)); \
+ \
+ SI void Exec_##name(StageList list, const void** ctx, STAGE_PARAMS()) { \
+ Exec_##name##_k(Ctx{*ctx}, src, dst, r, g, b, a, i); \
+ ++list.fn; ++ctx; \
+ CALL_NEXT; \
+ } \
+ \
+ SI void Exec_##name##_k(arg, STAGE_PARAMS(&))
+
+ #define STAGE(name, arg) \
+ DECLARE_STAGE(name, arg, [[clang::musttail]] return (*list.fn)(list, ctx, src, dst, \
+ r, g, b, a, i))
+
+ #define FINAL_STAGE(name, arg) \
+ DECLARE_STAGE(name, arg, /* Stop executing stages and return to the caller. */)
+
+#else
+
+ #define DECLARE_STAGE(name, arg) \
+ SI void Exec_##name##_k(arg, STAGE_PARAMS(&)); \
+ \
+ SI void Exec_##name(const void* ctx, STAGE_PARAMS(&)) { \
+ Exec_##name##_k(Ctx{ctx}, src, dst, r, g, b, a, i); \
+ } \
+ \
+ SI void Exec_##name##_k(arg, STAGE_PARAMS(&))
+
+ #define STAGE(name, arg) DECLARE_STAGE(name, arg)
+ #define FINAL_STAGE(name, arg) DECLARE_STAGE(name, arg)
+
+#endif
STAGE(load_a8, NoCtx) {
a = F_from_U8(load<U8>(src + 1*i));
@@ -1208,7 +1228,7 @@
clut(b2a, &r,&g,&b,&a);
}
-// From here on down, the store_ ops are all "final stages," terminating the tail-call recursion.
+// From here on down, the store_ ops are all "final stages," terminating processing of this group.
FINAL_STAGE(store_a8, NoCtx) {
store(dst + 1*i, cast<U8>(to_fixed(a * 255)));
@@ -1446,31 +1466,58 @@
#endif
}
-SI void exec_stages(StageList list, const void** contexts, const char* src, char* dst, int i) {
- (*list.fn)(list, contexts, src, dst, F0, F0, F0, F1, i);
-}
+#if SKCMS_HAS_MUSTTAIL
+
+ SI void exec_stages(StageFn* stages, const void** contexts, const char* src, char* dst, int i) {
+ (*stages)({stages}, contexts, src, dst, F0, F0, F0, F1, i);
+ }
+
+#else
+
+ static void exec_stages(const Op* ops, const void** contexts,
+ const char* src, char* dst, int i) {
+ F r = F0, g = F0, b = F0, a = F1;
+ while (true) {
+ switch (*ops++) {
+#define M(name) case Op::name: Exec_##name(*contexts++, src, dst, r, g, b, a, i); break;
+ SKCMS_WORK_OPS(M)
+#undef M
+#define M(name) case Op::name: Exec_##name(*contexts++, src, dst, r, g, b, a, i); return;
+ SKCMS_STORE_OPS(M)
+#undef M
+ }
+ }
+ }
+
+#endif
// NOLINTNEXTLINE(misc-definitions-in-headers)
-void run_program(const Op* program, const void** contexts, ptrdiff_t programSize,
+void run_program(const Op* program, const void** contexts, SKCMS_MAYBE_UNUSED ptrdiff_t programSize,
const char* src, char* dst, int n,
const size_t src_bpp, const size_t dst_bpp) {
+#if SKCMS_HAS_MUSTTAIL
// Convert the program into an array of tailcall stages.
StageFn stages[32];
assert(programSize <= ARRAY_COUNT(stages));
static constexpr StageFn kStageFns[] = {
#define M(name) &Exec_##name,
- SKCMS_ALL_OPS(M)
+ SKCMS_WORK_OPS(M)
+ SKCMS_STORE_OPS(M)
#undef M
};
for (ptrdiff_t index = 0; index < programSize; ++index) {
stages[index] = kStageFns[(int)program[index]];
}
+#else
+ // Use the op array as-is.
+ const Op* stages = program;
+#endif
int i = 0;
while (n >= N) {
- exec_stages({stages}, contexts, src, dst, i);
+ exec_stages(stages, contexts, src, dst, i);
i += N;
n -= N;
}
@@ -1478,7 +1525,7 @@
char tmp[4*4*N] = {0};
memcpy(tmp, (const char*)src + (size_t)i*src_bpp, (size_t)n*src_bpp);
- exec_stages({stages}, contexts, tmp, tmp, 0);
+ exec_stages(stages, contexts, tmp, tmp, 0);
memcpy((char*)dst + (size_t)i*dst_bpp, tmp, (size_t)n*dst_bpp);
}
}
diff --git a/src/skcms_Transform.h b/src/skcms_Transform.h
index 51391a0..049bf01 100644
--- a/src/skcms_Transform.h
+++ b/src/skcms_Transform.h
@@ -17,7 +17,7 @@
/** All transform ops */
-#define SKCMS_ALL_OPS(M) \
+#define SKCMS_WORK_OPS(M) \
M(load_a8) \
M(load_g8) \
M(load_4444) \
@@ -34,6 +34,7 @@
M(load_hhhh) \
M(load_fff) \
M(load_ffff) \
+ \
M(swap_rb) \
M(clamp) \
M(invert) \
@@ -82,27 +83,30 @@
M(table_a) \
\
M(clut_A2B) \
- M(clut_B2A) \
- M(store_a8) \
- M(store_g8) \
- M(store_4444) \
- M(store_565) \
- M(store_888) \
- M(store_8888) \
- M(store_1010102) \
- M(store_161616LE) \
- M(store_16161616LE) \
- M(store_161616BE) \
- M(store_16161616BE) \
- M(store_101010x_XR) \
- M(store_hhh) \
- M(store_hhhh) \
- M(store_fff) \
+ M(clut_B2A)
+
+#define SKCMS_STORE_OPS(M) \
+ M(store_a8) \
+ M(store_g8) \
+ M(store_4444) \
+ M(store_565) \
+ M(store_888) \
+ M(store_8888) \
+ M(store_1010102) \
+ M(store_161616LE) \
+ M(store_16161616LE) \
+ M(store_161616BE) \
+ M(store_16161616BE) \
+ M(store_101010x_XR) \
+ M(store_hhh) \
+ M(store_hhhh) \
+ M(store_fff) \
M(store_ffff)
enum class Op : int {
#define M(op) op,
- SKCMS_ALL_OPS(M)
+ SKCMS_WORK_OPS(M)
+ SKCMS_STORE_OPS(M)
#undef M
};
diff --git a/src/skcms_internals.h b/src/skcms_internals.h
index 9c0c89c..3871ea3 100644
--- a/src/skcms_internals.h
+++ b/src/skcms_internals.h
@@ -26,7 +26,7 @@
#define SKCMS_FALLTHROUGH [[clang::fallthrough]]
#endif
- #ifndef SKCMS_MUSTTAIL
+ #ifndef SKCMS_HAS_MUSTTAIL
// [[clang::musttail]] is great for performance, but it's not well supported and we run into
// a variety of problems when we use it. Fortunately, it's an optional feature that doesn't
// affect correctness, and usually the compiler will generate a tail-call even for us
@@ -47,9 +47,7 @@
&& !defined(__arm__) \
&& !defined(__riscv) \
&& !defined(_WIN32) && !defined(__SYMBIAN32__)
- #define SKCMS_MUSTTAIL [[clang::musttail]]
- #else
- #define SKCMS_MUSTTAIL
+ #define SKCMS_HAS_MUSTTAIL 1
#endif
#endif
#endif
@@ -57,8 +55,8 @@
#ifndef SKCMS_FALLTHROUGH
#define SKCMS_FALLTHROUGH
#endif
-#ifndef SKCMS_MUSTTAIL
- #define SKCMS_MUSTTAIL
+#ifndef SKCMS_HAS_MUSTTAIL
+ #define SKCMS_HAS_MUSTTAIL 0
#endif
#if defined(__clang__)
