From 121ab703a28987ed234584357bd3aaa84aace33d Mon Sep 17 00:00:00 2001
From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Mon, 24 Jun 2019 23:43:06 +0200
Subject: [PATCH] mimalloc: offer a build-time option to enable it

By defining `USE_MIMALLOC`, Git can now be compiled with that
nicely-fast and small allocator.

Note that we have to disable a couple `DEVELOPER` options to build
mimalloc's source code, as it makes heavy use of declarations after
statements, among other things that disagree with Git's conventions.

We even have to silence some GCC warnings in non-DEVELOPER mode. For
example, the `-Wno-array-bounds` flag is needed because in `-O2` builds,
trying to call `NtCurrentTeb()` (which `_mi_thread_id()` does on
Windows) causes the bogus warning about a system header, likely related
to https://sourceforge.net/p/mingw-w64/mailman/message/37674519/ and to
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578:

C:/git-sdk-64-minimal/mingw64/include/psdk_inc/intrin-impl.h:838:1:
        error: array subscript 0 is outside array bounds of 'long long unsigned int[0]' [-Werror=array-bounds]
  838 | __buildreadseg(__readgsqword, unsigned __int64, "gs", "q")
      | ^~~~~~~~~~~~~~

Also: The `mimalloc` library uses C11-style atomics, therefore we must
require that standard when compiling with GCC if we want to use
`mimalloc` (instead of requiring "only" C99). This is what we do in the
CMake definition already, therefore this commit does not need to touch
`contrib/buildsystems/`.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 Makefile              | 42 ++++++++++++++++++++++++++++++++++++++++++
 compat/.gitattributes |  1 +
 compat/posix.h        | 10 ++++++++++
 config.mak.dev        |  2 ++
 config.mak.uname      |  2 +-
 5 files changed, 56 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 2f490d402e..f39ece63f5 100644
--- a/Makefile
+++ b/Makefile
@@ -1507,6 +1507,7 @@ BUILTIN_OBJS += builtin/write-tree.o
 # upstream unnecessarily (making merging in future changes easier).
 THIRD_PARTY_SOURCES += compat/inet_ntop.c
 THIRD_PARTY_SOURCES += compat/inet_pton.c
+THIRD_PARTY_SOURCES += compat/mimalloc/%
 THIRD_PARTY_SOURCES += compat/obstack.%
 THIRD_PARTY_SOURCES += compat/poll/%
 THIRD_PARTY_SOURCES += compat/regex/%
@@ -2262,6 +2263,47 @@ ifdef NATIVE_CRLF
 	BASIC_CFLAGS += -DNATIVE_CRLF
 endif
 
+ifdef USE_MIMALLOC
+	MIMALLOC_OBJS = \
+		compat/mimalloc/alloc-aligned.o \
+		compat/mimalloc/alloc.o \
+		compat/mimalloc/arena.o \
+		compat/mimalloc/bitmap.o \
+		compat/mimalloc/heap.o \
+		compat/mimalloc/init.o \
+		compat/mimalloc/libc.o \
+		compat/mimalloc/options.o \
+		compat/mimalloc/os.o \
+		compat/mimalloc/page.o \
+		compat/mimalloc/random.o \
+		compat/mimalloc/prim/prim.o \
+		compat/mimalloc/segment.o \
+		compat/mimalloc/segment-map.o \
+		compat/mimalloc/stats.o
+
+	COMPAT_CFLAGS += -Icompat/mimalloc -DMI_DEBUG=0 -DUSE_MIMALLOC --std=gnu11
+	COMPAT_OBJS += $(MIMALLOC_OBJS)
+
+$(MIMALLOC_OBJS): COMPAT_CFLAGS += -DBANNED_H
+
+$(MIMALLOC_OBJS): COMPAT_CFLAGS += \
+	-DMI_WIN_USE_FLS \
+	-Wno-attributes \
+	-Wno-unknown-pragmas \
+	-Wno-unused-function \
+	-Wno-array-bounds
+
+ifdef DEVELOPER
+$(MIMALLOC_OBJS): COMPAT_CFLAGS += \
+	-Wno-pedantic \
+	-Wno-declaration-after-statement \
+	-Wno-old-style-definition \
+	-Wno-missing-prototypes \
+	-Wno-implicit-function-declaration
+endif
+endif
+
+
 ifdef OVERRIDE_STRDUP
 	COMPAT_CFLAGS += -DOVERRIDE_STRDUP
 	COMPAT_OBJS += compat/strdup.o
diff --git a/compat/.gitattributes b/compat/.gitattributes
index 40dbfb170d..2b5a66a3b3 100644
--- a/compat/.gitattributes
+++ b/compat/.gitattributes
@@ -1 +1,2 @@
 /zlib-uncompress2.c	whitespace=-indent-with-non-tab,-trailing-space
+/mimalloc/**/*	whitespace=-trailing-space
diff --git a/compat/posix.h b/compat/posix.h
index 09447e33a7..ffee39f391 100644
--- a/compat/posix.h
+++ b/compat/posix.h
@@ -176,6 +176,16 @@ typedef unsigned long uintptr_t;
 #define _ALL_SOURCE 1
 #endif
 
+#ifdef USE_MIMALLOC
+#include "mimalloc.h"
+#define malloc mi_malloc
+#define calloc mi_calloc
+#define realloc mi_realloc
+#define free mi_free
+#define strdup mi_strdup
+#define strndup mi_strndup
+#endif
+
 #ifdef MKDIR_WO_TRAILING_SLASH
 #define mkdir(a,b) compat_mkdir_wo_trailing_slash((a),(b))
 int compat_mkdir_wo_trailing_slash(const char*, mode_t);
diff --git a/config.mak.dev b/config.mak.dev
index eecb12c111..40eddf16ee 100644
--- a/config.mak.dev
+++ b/config.mak.dev
@@ -22,8 +22,10 @@ endif
 
 ifneq ($(uname_S),FreeBSD)
 ifneq ($(or $(filter gcc6,$(COMPILER_FEATURES)),$(filter clang7,$(COMPILER_FEATURES))),)
+ifndef USE_MIMALLOC
 DEVELOPER_CFLAGS += -std=gnu99
 endif
+endif
 else
 # FreeBSD cannot limit to C99 because its system headers unconditionally
 # rely on C11 features.
diff --git a/config.mak.uname b/config.mak.uname
index 58960eadb4..5e0d6f0769 100644
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -509,7 +509,7 @@ endif
 	CC = compat/vcbuild/scripts/clink.pl
 	AR = compat/vcbuild/scripts/lib.pl
 	CFLAGS =
-	BASIC_CFLAGS = -nologo -I. -Icompat/vcbuild/include -DWIN32 -D_CONSOLE -DHAVE_STRING_H -D_CRT_SECURE_NO_WARNINGS -D_CRT_NONSTDC_NO_DEPRECATE
+	BASIC_CFLAGS = -nologo -I. -Icompat/vcbuild/include -DWIN32 -D_CONSOLE -DHAVE_STRING_H -D_CRT_SECURE_NO_WARNINGS -D_CRT_NONSTDC_NO_DEPRECATE -MP -std:c11
 	COMPAT_OBJS = compat/msvc.o compat/winansi.o \
 		compat/win32/flush.o \
 		compat/win32/path-utils.o \