From: Nick Terrell <terrelln@fb.com>
Date: Tue, 16 Nov 2021 00:57:00 +0000 (-0800)
Subject: [linux-kernel] Don't inline function in zstd_opt.c
X-Git-Tag: v1.4.10~3
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b9302410bf3fd066b776deb18b06f37fe290a0dd;p=thirdparty%2Fzstd.git

[linux-kernel] Don't inline function in zstd_opt.c

The optimal parser is unlikely to be used in the linux kernel in
practice. There is no reason these functions should be force inlined,
since we aren't gaining anything, and are losing build size.

| Compiler | Before (Bytes) | After (Bytes) | Delta (Bytes) |
|----------|----------------|---------------|---------------|
| gcc-11   |        1142090 |        952754 |       -189336 |
| clang-12 |        1228402 |        976290 |       -252112 |

This is a temporary solution pending the resolution of Issue #2862 in
the `dev` branch.
---

diff --git a/contrib/linux-kernel/Makefile b/contrib/linux-kernel/Makefile
index fbd4a4ab1..b1c7f6f72 100644
--- a/contrib/linux-kernel/Makefile
+++ b/contrib/linux-kernel/Makefile
@@ -39,7 +39,6 @@ libzstd:
 		-DZSTD_ADDRESS_SANITIZER=0 \
 		-DZSTD_MEMORY_SANITIZER=0 \
 		-DZSTD_COMPRESS_HEAPMODE=1 \
-		-UZSTD_NO_INLINE \
 		-UNO_PREFETCH \
 		-U__cplusplus \
 		-UZSTD_DLL_EXPORT \
@@ -53,7 +52,8 @@ libzstd:
 		-RZSTD_FALLTHROUGH=fallthrough \
 		-DZSTD_HAVE_WEAK_SYMBOLS=0 \
 		-DZSTD_TRACE=0 \
-		-DZSTD_NO_TRACE
+		-DZSTD_NO_TRACE \
+		-DZSTD_LINUX_KERNEL
 	mv linux/lib/zstd/zstd.h linux/include/linux/zstd_lib.h
 	mv linux/lib/zstd/common/zstd_errors.h linux/include/linux/
 	cp linux_zstd.h linux/include/linux/zstd.h
diff --git a/contrib/linux-kernel/test/macro-test.sh b/contrib/linux-kernel/test/macro-test.sh
index c688ac03b..3363cfcdf 100755
--- a/contrib/linux-kernel/test/macro-test.sh
+++ b/contrib/linux-kernel/test/macro-test.sh
@@ -36,7 +36,6 @@ test_not_present "ZSTD_NO_INTRINSICS"
 test_not_present "ZSTD_NO_UNUSED_FUNCTIONS"
 test_not_present "ZSTD_LEGACY_SUPPORT"
 test_not_present "STATIC_BMI2"
-test_not_present "ZSTD_NO_INLINE"
 test_not_present "ZSTD_DLL_EXPORT"
 test_not_present "ZSTD_DLL_IMPORT"
 test_not_present "__ICCARM__"
diff --git a/lib/compress/zstd_opt.c b/lib/compress/zstd_opt.c
index d9fbfef1f..c1b311eff 100644
--- a/lib/compress/zstd_opt.c
+++ b/lib/compress/zstd_opt.c
@@ -8,6 +8,20 @@
  * You may select, at your option, one of the above-listed licenses.
  */
 
+/**
+ * Disable inlining for the optimal parser for the kernel build.
+ * It is unlikely to be used in the kernel, and where it is used
+ * latency shouldn't matter because it is very slow to begin with.
+ * We prefer a ~180KB binary size win over faster optimal parsing.
+ *
+ * TODO(https://github.com/facebook/zstd/issues/2862):
+ * Improve the code size of the optimal parser in general, so we
+ * don't need this hack for the kernel build.
+ */
+#ifdef ZSTD_LINUX_KERNEL
+#define ZSTD_NO_INLINE 1
+#endif
+
 #include "zstd_compress_internal.h"
 #include "hist.h"
 #include "zstd_opt.h"
@@ -894,7 +908,7 @@ static void ZSTD_optLdm_processMatchCandidate(ZSTD_optLdm_t* optLdm, ZSTD_match_
              */
             U32 posOvershoot = currPosInBlock - optLdm->endPosInBlock;
             ZSTD_optLdm_skipRawSeqStoreBytes(&optLdm->seqStore, posOvershoot);
-        } 
+        }
         ZSTD_opt_getNextMatchAndUpdateSeqStore(optLdm, currPosInBlock, remainingBytes);
     }
     ZSTD_optLdm_maybeAddMatch(matches, nbMatches, optLdm, currPosInBlock);