Merge bitcoin/bitcoin#30257: build: Remove --enable-gprof

fa780e1c25e8e98253e32d93db65f78a0092433f build: Remove --enable-gprof (MarcoFalke)

Pull request description:

  It is unclear what benefit this option has, given that:

  * `gprof` requires re-compilation (`perf` and other tools can instead be used on existing executables)
  * `gprof` requires hardening to be disabled
  * `gprof` doesn't work with `clang`
  * `perf` is documented in the dev-notes, and test notes, and embedded into the functional test framework; `gprof` isn't
  * Anyone really wanting to use it could pass the required flags to `./configure`
  * I couldn't find any mention of the use of `gprof` in the discussions in this repo, apart from the initial pull request adding it (cfaac2a60f3ac63ae8deccb03d88bd559449b78c)
  * Keeping it means that it needs to be maintained and ported to CMake

  Fix all issues by removing it.

ACKs for top commit:
  TheCharlatan:
    ACK fa780e1c25e8e98253e32d93db65f78a0092433f
  hebasto:
    ACK fa780e1c25e8e98253e32d93db65f78a0092433f, I have reviewed the code and it looks OK.
  willcl-ark:
    crACK fa780e1c25e8e98253e32d93db65f78a0092433f

Tree-SHA512: 0a9ff363ac2bec8b743878a4e3147f18bc16823d00c5007568432c36320bd0199b13b6d0ce828a9a83c2cc434c058afaa64eb2eccfbd93ed85b81ce10c41760c

3 files changed, 6 insertions, 39 deletions

diff --git a/configure.ac b/configure.ac
index eff34fa9e9..ab369cc98a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -206,9 +206,9 @@ AC_ARG_WITH([qrencode],
 
 AC_ARG_ENABLE([hardening],
   [AS_HELP_STRING([--disable-hardening],
-  [do not attempt to harden the resulting executables (default is to harden when possible)])],
+  [do not attempt to harden the resulting executables (default is to harden)])],
   [use_hardening=$enableval],
-  [use_hardening=auto])
+  [use_hardening=yes])
 
 AC_ARG_ENABLE([reduce-exports],
   [AS_HELP_STRING([--enable-reduce-exports],
@@ -281,13 +281,6 @@ AC_ARG_WITH([sanitizers],
                     [comma separated list of extra sanitizers to build with (default is none enabled)])],
     [use_sanitizers=$withval])
 
-dnl Enable gprof profiling
-AC_ARG_ENABLE([gprof],
-    [AS_HELP_STRING([--enable-gprof],
-                    [use gprof profiling compiler flags (default is no)])],
-    [enable_gprof=$enableval],
-    [enable_gprof=no])
-
 dnl Turn warnings into errors
 AC_ARG_ENABLE([werror],
     [AS_HELP_STRING([--enable-werror],
@@ -844,30 +837,12 @@ if test "$ac_cv_sys_large_files" != "" &&
   CORE_CPPFLAGS="$CORE_CPPFLAGS -D_LARGE_FILES=$ac_cv_sys_large_files"
 fi
 
-if test "$enable_gprof" = "yes"; then
-    dnl -pg is incompatible with -pie. Since hardening and profiling together doesn't make sense,
-    dnl we simply make them mutually exclusive here. Additionally, hardened toolchains may force
-    dnl -pie by default, in which case it needs to be turned off with -no-pie.
-
-    if test "$use_hardening" = "yes"; then
-        AC_MSG_ERROR([gprof profiling is not compatible with hardening. Reconfigure with --disable-hardening or --disable-gprof])
-    fi
-    use_hardening=no
-    AX_CHECK_COMPILE_FLAG([-pg],[GPROF_CXXFLAGS="-pg"],
-        [AC_MSG_ERROR([gprof profiling requested but not available])], [$CXXFLAG_WERROR])
-
-    AX_CHECK_LINK_FLAG([-no-pie], [GPROF_LDFLAGS="-no-pie"])
-    AX_CHECK_LINK_FLAG([-pg], [GPROF_LDFLAGS="$GPROF_LDFLAGS -pg"],
-        [AC_MSG_ERROR([gprof profiling requested but not available])], [$GPROF_LDFLAGS])
-fi
-
 if test "$TARGET_OS" != "windows"; then
   dnl All windows code is PIC, forcing it on just adds useless compile warnings
   AX_CHECK_COMPILE_FLAG([-fPIC], [PIC_FLAGS="-fPIC"])
 fi
 
 if test "$use_hardening" != "no"; then
-  use_hardening=yes
   AX_CHECK_COMPILE_FLAG([-Wstack-protector], [HARDENED_CXXFLAGS="$HARDENED_CXXFLAGS -Wstack-protector"])
   AX_CHECK_COMPILE_FLAG([-fstack-protector-all], [HARDENED_CXXFLAGS="$HARDENED_CXXFLAGS -fstack-protector-all"])
 
@@ -1684,8 +1659,6 @@ AC_SUBST(WARN_CXXFLAGS)
 AC_SUBST(NOWARN_CXXFLAGS)
 AC_SUBST(DEBUG_CXXFLAGS)
 AC_SUBST(ERROR_CXXFLAGS)
-AC_SUBST(GPROF_CXXFLAGS)
-AC_SUBST(GPROF_LDFLAGS)
 AC_SUBST(HARDENED_CXXFLAGS)
 AC_SUBST(HARDENED_CPPFLAGS)
 AC_SUBST(HARDENED_LDFLAGS)
@@ -1793,7 +1766,6 @@ echo "  with natpmp     = $use_natpmp"
 echo "  USDT tracing    = $use_usdt"
 echo "  sanitizers      = $use_sanitizers"
 echo "  debug enabled   = $enable_debug"
-echo "  gprof enabled   = $enable_gprof"
 echo "  werror          = $enable_werror"
 echo
 echo "  target os       = $host_os"
@@ -1803,8 +1775,8 @@ echo "  CC              = $CC"
 echo "  CFLAGS          = $PTHREAD_CFLAGS $SANITIZER_CFLAGS $CFLAGS"
 echo "  CPPFLAGS        = $DEBUG_CPPFLAGS $HARDENED_CPPFLAGS $CORE_CPPFLAGS $CPPFLAGS"
 echo "  CXX             = $CXX"
-echo "  CXXFLAGS        = $CORE_CXXFLAGS $DEBUG_CXXFLAGS $HARDENED_CXXFLAGS $WARN_CXXFLAGS $NOWARN_CXXFLAGS $ERROR_CXXFLAGS $GPROF_CXXFLAGS $SANITIZER_CXXFLAGS $CXXFLAGS"
-echo "  LDFLAGS         = $PTHREAD_LIBS $HARDENED_LDFLAGS $GPROF_LDFLAGS $SANITIZER_LDFLAGS $CORE_LDFLAGS $LDFLAGS"
+echo "  CXXFLAGS        = $CORE_CXXFLAGS $DEBUG_CXXFLAGS $HARDENED_CXXFLAGS $WARN_CXXFLAGS $NOWARN_CXXFLAGS $ERROR_CXXFLAGS $SANITIZER_CXXFLAGS $CXXFLAGS"
+echo "  LDFLAGS         = $PTHREAD_LIBS $HARDENED_LDFLAGS $SANITIZER_LDFLAGS $CORE_LDFLAGS $LDFLAGS"
 echo "  AR              = $AR"
 echo "  ARFLAGS         = $ARFLAGS"
 echo
diff --git a/doc/developer-notes.md b/doc/developer-notes.md
index 7e55962471..eb2bb41aa4 100644
--- a/doc/developer-notes.md
+++ b/doc/developer-notes.md
@@ -13,7 +13,6 @@ Developer Notes
     - [Development tips and tricks](#development-tips-and-tricks)
         - [Compiling for debugging](#compiling-for-debugging)
         - [Show sources in debugging](#show-sources-in-debugging)
-        - [Compiling for gprof profiling](#compiling-for-gprof-profiling)
         - [`debug.log`](#debuglog)
         - [Signet, testnet, and regtest modes](#signet-testnet-and-regtest-modes)
         - [DEBUG_LOCKORDER](#debug_lockorder)
@@ -386,10 +385,6 @@ ln -s /path/to/project/root/src src
 
 3. Use `debugedit` to modify debug information in the binary.
 
-### Compiling for gprof profiling
-
-Run configure with the `--enable-gprof` option, then make.
-
 ### `debug.log`
 
 If the code is behaving strangely, take a look in the `debug.log` file in the data directory;
diff --git a/src/Makefile.am b/src/Makefile.am
index 87bb2b945c..abbc5cdc1f 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -8,8 +8,8 @@ print-%: FORCE
 
 DIST_SUBDIRS = secp256k1
 
-AM_LDFLAGS = $(LIBTOOL_LDFLAGS) $(HARDENED_LDFLAGS) $(GPROF_LDFLAGS) $(SANITIZER_LDFLAGS) $(CORE_LDFLAGS)
-AM_CXXFLAGS = $(CORE_CXXFLAGS) $(DEBUG_CXXFLAGS) $(HARDENED_CXXFLAGS) $(WARN_CXXFLAGS) $(NOWARN_CXXFLAGS) $(ERROR_CXXFLAGS) $(GPROF_CXXFLAGS) $(SANITIZER_CXXFLAGS)
+AM_LDFLAGS = $(LIBTOOL_LDFLAGS) $(HARDENED_LDFLAGS) $(SANITIZER_LDFLAGS) $(CORE_LDFLAGS)
+AM_CXXFLAGS = $(CORE_CXXFLAGS) $(DEBUG_CXXFLAGS) $(HARDENED_CXXFLAGS) $(WARN_CXXFLAGS) $(NOWARN_CXXFLAGS) $(ERROR_CXXFLAGS) $(SANITIZER_CXXFLAGS)
 AM_OBJCXXFLAGS = $(AM_CXXFLAGS)
 AM_CPPFLAGS = $(DEBUG_CPPFLAGS) $(HARDENED_CPPFLAGS) $(CORE_CPPFLAGS)
 AM_LIBTOOLFLAGS = --preserve-dup-deps