Introduce XXH_SIZE_OPT and XXH_NO_STREAM

.github/workflows/ci.yml

@@ -139,12 +139,23 @@ jobs:
       run: |
         CFLAGS="-Wall -Wextra -Werror" make DISPATCH=1 clean default
 
+    - name: XXH_SIZE_OPT == 2
+      if: always()
+      run: |
+        CFLAGS="-Os -DXXH_SIZE_OPT=2 -Wall -Wextra -Werror" make clean xxhsum
+
     - name: noxxh3test
       if: always()
       run: |
         # check library can be compiled with XXH_NO_XXH3, resulting in no XXH3_* symbol
         make clean noxxh3test
 
+    - name: nostreamtest
+      if: always()
+      run: |
+        # check library can be compiled with XXH_NO_STREAM, resulting in no streaming symbols
+        make clean noxxh3test
+
     - name: make avx512f
       if: ${{ matrix.avx512 == 'true' }}
       run: |

Makefile

@@ -342,6 +342,16 @@ noxxh3test: xxhash.c
 	$(NM) $(OFILE) | $(GREP) XXH3_ ; test $$? -eq 1
 	$(RM) $(OFILE)
 
+.PHONY: nostreamtest
+nostreamtest: CPPFLAGS += -DXXH_NO_STREAM
+nostreamtest: CFLAGS += -Werror -pedantic -Wno-long-long  # XXH64 requires long long support
+nostreamtest: OFILE = xxh_nostream.o
+nostreamtest: xxhash.c
+	@echo ---- test compilation without streaming ----
+	$(CC) $(FLAGS) -c $^ -o $(OFILE)
+	$(NM) $(OFILE) | $(GREP) update ; test $$? -eq 1
+	$(RM) $(OFILE)
+
 .PHONY: nostdlibtest
 nostdlibtest: CPPFLAGS += -DXXH_NO_STDLIB
 nostdlibtest: CFLAGS += -Werror -pedantic -Wno-long-long  # XXH64 requires long long support

README.md

@@ -113,6 +113,10 @@ The following macros can be set at compilation time to modify libxxhash's behavi
 - `XXH_VECTOR` : manually select a vector instruction set (default: auto-selected at compilation time). Available instruction sets are `XXH_SCALAR`, `XXH_SSE2`, `XXH_AVX2`, `XXH_AVX512`, `XXH_NEON` and `XXH_VSX`. Compiler may require additional flags to ensure proper support (for example, `gcc` on linux will require `-mavx2` for AVX2, and `-mavx512f` for AVX512).
 - `XXH_NO_PREFETCH` : disable prefetching. Some platforms or situations may perform better without prefetching. XXH3 only.
 - `XXH_PREFETCH_DIST` : select prefetching distance. For close-to-metal adaptation to specific hardware platforms. XXH3 only.
+- `XXH_NO_STREAM`: Disables the streaming API, limiting it to single shot variants only.
+- `XXH_SIZE_OPT`: `0`: default, optimize for speed
+                  `1`: default for `-Os` and `-Oz`: disables some speed hacks for size optimization
+                  `2`: makes code as small as possible, performance may cry
 - `XXH_NO_INLINE_HINTS`: By default, xxHash uses `__attribute__((always_inline))` and `__forceinline` to improve performance at the cost of code size.
                          Defining this macro to 1 will mark all internal functions as `static`, allowing the compiler to decide whether to inline a function or not.
                          This is very useful when optimizing for smallest binary size,