From 1ec505b75159af4f206ed3864ccb0df6378d0835 Mon Sep 17 00:00:00 2001
From: guangli-dai <gdai@meta.com>
Date: Tue, 28 Jul 2026 14:39:30 -0700
Subject: [PATCH] Move FMTd32-family printf macros to OS layer

Move macros defining the FMT module to OS layer.
---
 include/jemalloc/internal/malloc_io.h      | 39 +++++-----------------
 include/jemalloc/internal/os.h             |  7 ++++
 include/jemalloc/internal/os/fmt.h         | 25 ++++++++++++++
 include/jemalloc/internal/os/posix/fmt.h   | 16 +++++++++
 include/jemalloc/internal/os/windows/fmt.h | 21 ++++++++++++
 5 files changed, 78 insertions(+), 30 deletions(-)
 create mode 100644 include/jemalloc/internal/os/fmt.h
 create mode 100644 include/jemalloc/internal/os/posix/fmt.h
 create mode 100644 include/jemalloc/internal/os/windows/fmt.h

diff --git a/include/jemalloc/internal/malloc_io.h b/include/jemalloc/internal/malloc_io.h
index 99b0fca3..54ee7332 100644
--- a/include/jemalloc/internal/malloc_io.h
+++ b/include/jemalloc/internal/malloc_io.h
@@ -3,36 +3,15 @@
 
 #include "jemalloc/internal/jemalloc_preamble.h"
 #include "jemalloc/internal/jemalloc_internal_types.h"
-
-#ifdef _WIN32
-#	ifdef _WIN64
-#		define FMT64_PREFIX "ll"
-#		define FMTPTR_PREFIX "ll"
-#	else
-#		define FMT64_PREFIX "ll"
-#		define FMTPTR_PREFIX ""
-#	endif
-#	define FMTd32 "d"
-#	define FMTu32 "u"
-#	define FMTx32 "x"
-#	define FMTd64 FMT64_PREFIX "d"
-#	define FMTu64 FMT64_PREFIX "u"
-#	define FMTx64 FMT64_PREFIX "x"
-#	define FMTdPTR FMTPTR_PREFIX "d"
-#	define FMTuPTR FMTPTR_PREFIX "u"
-#	define FMTxPTR FMTPTR_PREFIX "x"
-#else
-#	include <inttypes.h>
-#	define FMTd32 PRId32
-#	define FMTu32 PRIu32
-#	define FMTx32 PRIx32
-#	define FMTd64 PRId64
-#	define FMTu64 PRIu64
-#	define FMTx64 PRIx64
-#	define FMTdPTR PRIdPTR
-#	define FMTuPTR PRIuPTR
-#	define FMTxPTR PRIxPTR
-#endif
+/*
+ * os/fmt.h directly (not the os.h umbrella): this header is itself included
+ * from os/posix/error.h (for malloc_snprintf's declaration), so pulling in
+ * the full os.h here would risk the same circular-include hazard os/error.h
+ * avoids by not going through the umbrella either. os/fmt.h is a leaf module
+ * (macros only, no dependency back on malloc_io.h or anything else), so
+ * including it alone is safe.
+ */
+#include "jemalloc/internal/os/fmt.h"
 
 /* Size of stack-allocated buffer passed to buferror(). */
 #define BUFERROR_BUF 64
diff --git a/include/jemalloc/internal/os.h b/include/jemalloc/internal/os.h
index b66a1943..b3b01c64 100644
--- a/include/jemalloc/internal/os.h
+++ b/include/jemalloc/internal/os.h
@@ -56,4 +56,11 @@
  */
 #include "jemalloc/internal/os/error.h"
 
+/*
+ * Printf format-specifier macros. malloc_io.h includes os/fmt.h directly
+ * (not via this umbrella) for the same early-reachability reason as
+ * os/error.h above. Included here too for discoverability.
+ */
+#include "jemalloc/internal/os/fmt.h"
+
 #endif /* JEMALLOC_INTERNAL_OS_H */
diff --git a/include/jemalloc/internal/os/fmt.h b/include/jemalloc/internal/os/fmt.h
new file mode 100644
index 00000000..520181cb
--- /dev/null
+++ b/include/jemalloc/internal/os/fmt.h
@@ -0,0 +1,25 @@
+#ifndef JEMALLOC_INTERNAL_OS_FMT_H
+#define JEMALLOC_INTERNAL_OS_FMT_H
+
+#include "jemalloc/internal/jemalloc_preamble.h"
+#include "jemalloc/internal/os/detect.h"
+
+/*
+ * Printf format-specifier macros for fixed-width and pointer-sized integers
+ * (FMTd32/FMTu32/FMTx32/FMTd64/FMTu64/FMTx64/FMTdPTR/FMTuPTR/FMTxPTR).
+ * Default: posix/ (<inttypes.h>'s PRId32 etc).  Override: Windows (MSVC's
+ * CRT historically didn't support the C99 <inttypes.h> macros the same way,
+ * so these are hand-rolled from an ll/I64-style prefix instead).
+ *
+ * Unlike other modules, this one defines only macros, no functions.
+ */
+
+#if defined(_WIN32)
+#  include "jemalloc/internal/os/windows/fmt.h"
+#elif defined(JEMALLOC_OS_POSIX)
+#  include "jemalloc/internal/os/posix/fmt.h"
+#else
+#  error "OS layer: no fmt backend for this platform; add os/<os>/fmt.h"
+#endif
+
+#endif /* JEMALLOC_INTERNAL_OS_FMT_H */
diff --git a/include/jemalloc/internal/os/posix/fmt.h b/include/jemalloc/internal/os/posix/fmt.h
new file mode 100644
index 00000000..1a71dcdd
--- /dev/null
+++ b/include/jemalloc/internal/os/posix/fmt.h
@@ -0,0 +1,16 @@
+#ifndef JEMALLOC_INTERNAL_OS_POSIX_FMT_H
+#define JEMALLOC_INTERNAL_OS_POSIX_FMT_H
+
+#include <inttypes.h>
+
+#define FMTd32 PRId32
+#define FMTu32 PRIu32
+#define FMTx32 PRIx32
+#define FMTd64 PRId64
+#define FMTu64 PRIu64
+#define FMTx64 PRIx64
+#define FMTdPTR PRIdPTR
+#define FMTuPTR PRIuPTR
+#define FMTxPTR PRIxPTR
+
+#endif /* JEMALLOC_INTERNAL_OS_POSIX_FMT_H */
diff --git a/include/jemalloc/internal/os/windows/fmt.h b/include/jemalloc/internal/os/windows/fmt.h
new file mode 100644
index 00000000..366c8988
--- /dev/null
+++ b/include/jemalloc/internal/os/windows/fmt.h
@@ -0,0 +1,21 @@
+#ifndef JEMALLOC_INTERNAL_OS_WINDOWS_FMT_H
+#define JEMALLOC_INTERNAL_OS_WINDOWS_FMT_H
+
+#ifdef _WIN64
+#  define FMT64_PREFIX "ll"
+#  define FMTPTR_PREFIX "ll"
+#else
+#  define FMT64_PREFIX "ll"
+#  define FMTPTR_PREFIX ""
+#endif
+#define FMTd32 "d"
+#define FMTu32 "u"
+#define FMTx32 "x"
+#define FMTd64 FMT64_PREFIX "d"
+#define FMTu64 FMT64_PREFIX "u"
+#define FMTx64 FMT64_PREFIX "x"
+#define FMTdPTR FMTPTR_PREFIX "d"
+#define FMTuPTR FMTPTR_PREFIX "u"
+#define FMTxPTR FMTPTR_PREFIX "x"
+
+#endif /* JEMALLOC_INTERNAL_OS_WINDOWS_FMT_H */