From 8740697791f99b7175e188f049663883c39e51b0 Mon Sep 17 00:00:00 2001
From: Thomas Preud'homme <thomas.preudhomme@linaro.org>
Date: Fri, 26 Oct 2018 16:21:09 +0100
Subject: [PATCH] [PATCH, libgcc/ARM] Optimize executable size when using
 softfloat fmul/dmul

Softfloat single precision and double precision floating-point
multiplication routines in libgcc share some code with the
floating-point division of their corresponding precision. As the code
is structured now, this leads to *all* division code being pulled in an
executable in softfloat mode even if only multiplication is
performed.

This patch create some new LIB1ASMFUNCS macros to also build files with
just the multiplication and shared code as weak symbols. By putting
these earlier in the static library, they can then be picked up when
only multiplication is used and they are overriden by the global
definition in the existing file containing both multiplication and
division code when division is needed.

The patch also removes changes made to the FUNC_START and ARM_FUNC_START
macros in r218124 since the intent was to put multiplication and
division code into their own section in a later patch to achieve the
same size optimization. That approach relied on specific section layout
to ensure multiplication and division were not too far from the shared
bit of code in order to the branches to be within range. Due to lack of
guarantee regarding section layout, in particular with all the
possibility of linker scripts, this approach was chosen instead. This
patch keeps the two testcases that were posted by Tony Wang (an Arm
employee at the time) on the mailing list to implement this approach
and adds a new one, hence the attribution.

ChangeLog entries are as follows:

*** gcc/ChangeLog ***

2018-11-14  Thomas Preud'homme  <thomas.preudhomme@linaro.org>

	* config/arm/elf.h: Update comment about condition that need to
	match with libgcc/config/arm/lib1funcs.S to also include
	libgcc/config/arm/t-arm.
	* doc/sourcebuild.texi (output-exists, output-exists-not): Rename
	subsubsection these directives are in to "Check for output files".
	Move scan-symbol to that section and add to it new scan-symbol-not
	directive.

*** gcc/testsuite/ChangeLog ***

2018-11-16  Tony Wang  <tony.wang@arm.com>
	    Thomas Preud'homme  <thomas.preudhomme@linaro.org>

	* lib/lto.exp (lto-execute): Define output_file and testname_with_flags
	to same value as execname.
	(scan-symbol): Move and rename to ...
	* lib/gcc-dg.exp (scan-symbol-common): This.  Adapt into a
	helper function returning true or false if a symbol is present.
	(scan-symbol): New procedure.
	(scan-symbol-not): Likewise.
	* gcc.target/arm/size-optimization-ieee-1.c: New testcase.
	* gcc.target/arm/size-optimization-ieee-2.c: Likewise.
	* gcc.target/arm/size-optimization-ieee-3.c: Likewise.

*** libgcc/ChangeLog ***

2018-11-16  Thomas Preud'homme  <thomas.preudhomme@linaro.org>

	* /config/arm/lib1funcs.S (FUNC_START): Remove unused sp_section
	parameter and corresponding code.
	(ARM_FUNC_START): Likewise in both definitions.
	Also update footer comment about condition that need to match with
	gcc/config/arm/elf.h to also include libgcc/config/arm/t-arm.
	* config/arm/ieee754-df.S (muldf3): Also build it if L_arm_muldf3 is
	defined.  Weakly define it in this case.
	* config/arm/ieee754-sf.S (mulsf3): Likewise with L_arm_mulsf3.
	* config/arm/t-elf (LIB1ASMFUNCS): Build _arm_muldf3.o and
	_arm_mulsf3.o before muldiv versions if targeting Thumb-1 only. Add
	comment to keep condition in sync with the one in
	libgcc/config/arm/lib1funcs.S and gcc/config/arm/elf.h.

Testing: Bootstrapped on arm-linux-gnueabihf and testsuite shows no
regression. Also built an arm-none-eabi cross compiler targeting
soft-float which also shows no regression. In particular newly added
tests and gcc.dg/lto/20081212-1 test pass.

Is this ok for stage3?

Best regards,

Thomas
---
 gcc/config/arm/elf.h                          |  2 +-
 gcc/doc/sourcebuild.texi                      |  9 +--
 .../gcc.target/arm/size-optimization-ieee-1.c | 33 ++++++++
 .../gcc.target/arm/size-optimization-ieee-2.c | 31 ++++++++
 .../gcc.target/arm/size-optimization-ieee-3.c | 33 ++++++++
 gcc/testsuite/lib/gcc-dg.exp                  | 76 +++++++++++++++++++
 gcc/testsuite/lib/lto.exp                     | 63 +++------------
 libgcc/config/arm/ieee754-df.S                | 17 ++++-
 libgcc/config/arm/ieee754-sf.S                | 16 +++-
 libgcc/config/arm/lib1funcs.S                 | 19 ++---
 libgcc/config/arm/t-elf                       | 16 ++++
 11 files changed, 243 insertions(+), 72 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/arm/size-optimization-ieee-1.c
 create mode 100644 gcc/testsuite/gcc.target/arm/size-optimization-ieee-2.c
 create mode 100644 gcc/testsuite/gcc.target/arm/size-optimization-ieee-3.c

diff --git a/gcc/config/arm/elf.h b/gcc/config/arm/elf.h
index ad3651ba841..1e00e99afc6 100644
--- a/gcc/config/arm/elf.h
+++ b/gcc/config/arm/elf.h
@@ -137,7 +137,7 @@
 
 /* Horrible hack: We want to prevent some libgcc routines being included
    for some multilibs.  The condition should match the one in
-   libgcc/config/arm/lib1funcs.S.  */
+   libgcc/config/arm/lib1funcs.S and libgcc/config/arm/t-elf.  */
 #if __ARM_ARCH_ISA_ARM || __ARM_ARCH_ISA_THUMB != 1
 #undef L_fixdfsi
 #undef L_fixunsdfsi
diff --git a/gcc/doc/sourcebuild.texi b/gcc/doc/sourcebuild.texi
index 89157079ffb..9bf59b81d87 100644
--- a/gcc/doc/sourcebuild.texi
+++ b/gcc/doc/sourcebuild.texi
@@ -2638,7 +2638,7 @@ Passes if @var{regex} does not match demangled text in the dump file with
 suffix @var{suffix}.
 @end table
 
-@subsubsection Verify that an output files exists or not
+@subsubsection Check for output files
 
 @table @code
 @item output-exists [@{ target/xfail @var{selector} @}]
@@ -2646,13 +2646,12 @@ Passes if compiler output file exists.
 
 @item output-exists-not [@{ target/xfail @var{selector} @}]
 Passes if compiler output file does not exist.
-@end table
-
-@subsubsection Check for LTO tests
 
-@table @code
 @item scan-symbol @var{regexp} [@{ target/xfail @var{selector} @}]
 Passes if the pattern is present in the final executable.
+
+@item scan-symbol-not @var{regexp} [@{ target/xfail @var{selector} @}]
+Passes if the pattern is absent from the final executable.
 @end table
 
 @subsubsection Checks for @command{gcov} tests
diff --git a/gcc/testsuite/gcc.target/arm/size-optimization-ieee-1.c b/gcc/testsuite/gcc.target/arm/size-optimization-ieee-1.c
new file mode 100644
index 00000000000..34090f20fec
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/size-optimization-ieee-1.c
@@ -0,0 +1,33 @@
+/* { dg-do link { target arm_soft_ok } } */
+/* { dg-options "-mfloat-abi=soft" } */
+
+int
+foo (void)
+{
+  volatile float a;
+  volatile float b;
+  volatile float c = a * b;
+  return 0;
+}
+
+int
+bar (void)
+{
+  volatile double a;
+  volatile double b;
+  volatile double c = a * b;
+  return 0;
+}
+
+int
+main (void)
+{
+  foo ();
+  bar ();
+  return 0;
+}
+
+/* { dg-final { scan-symbol "__aeabi_fmul" } } */
+/* { dg-final { scan-symbol "__aeabi_dmul" } } */
+/* { dg-final { scan-symbol-not "__aeabi_fdiv" } } */
+/* { dg-final { scan-symbol-not "__aeabi_ddiv" } } */
diff --git a/gcc/testsuite/gcc.target/arm/size-optimization-ieee-2.c b/gcc/testsuite/gcc.target/arm/size-optimization-ieee-2.c
new file mode 100644
index 00000000000..75337894a9c
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/size-optimization-ieee-2.c
@@ -0,0 +1,31 @@
+/* { dg-do link { target arm_soft_ok } } */
+/* { dg-options "-mfloat-abi=soft" } */
+
+int
+foo (void)
+{
+  volatile float a;
+  volatile float b;
+  volatile float c = a / b;
+  return 0;
+}
+
+int
+bar (void)
+{
+  volatile double a;
+  volatile double b;
+  volatile double c = a / b;
+  return 0;
+}
+
+int
+main (void)
+{
+  foo ();
+  bar ();
+  return 0;
+}
+
+/* { dg-final { scan-symbol "__aeabi_fdiv" } } */
+/* { dg-final { scan-symbol "__aeabi_ddiv" } } */
diff --git a/gcc/testsuite/gcc.target/arm/size-optimization-ieee-3.c b/gcc/testsuite/gcc.target/arm/size-optimization-ieee-3.c
new file mode 100644
index 00000000000..63c92b3bbb7
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/size-optimization-ieee-3.c
@@ -0,0 +1,33 @@
+/* { dg-do link { target arm_soft_ok } } */
+/* { dg-options "-mfloat-abi=soft" } */
+
+int
+foo (void)
+{
+  volatile float a;
+  volatile float b;
+  volatile float c = a * b + a / b;
+  return 0;
+}
+
+int
+bar (void)
+{
+  volatile double a;
+  volatile double b;
+  volatile double c = a * b + a / b;
+  return 0;
+}
+
+int
+main (void)
+{
+  foo ();
+  bar ();
+  return 0;
+}
+
+/* { dg-final { scan-symbol "__aeabi_fmul" } } */
+/* { dg-final { scan-symbol "__aeabi_dmul" } } */
+/* { dg-final { scan-symbol "__aeabi_fdiv" } } */
+/* { dg-final { scan-symbol "__aeabi_ddiv" } } */
diff --git a/gcc/testsuite/lib/gcc-dg.exp b/gcc/testsuite/lib/gcc-dg.exp
index c33a50c0b13..0472b63f94c 100644
--- a/gcc/testsuite/lib/gcc-dg.exp
+++ b/gcc/testsuite/lib/gcc-dg.exp
@@ -1236,5 +1236,81 @@ proc gdb-exists { args } {
     return 0;
 }
 
+# Helper function for scan-symbol and scan-symbol-not. It scans a symbol in
+# the final executable and return 1 if present, otherwise fail.
+#
+# Argument 0 is the regexp to match.
+# Argument 1 handles expected failures and the like
+proc scan-symbol-common { scan_directive args } {
+    global nm
+    global base_dir
+
+    # Access variable from gcc-dg-test-1 or lto-execute.
+    upvar 3 output_file output_file
+
+    if { [llength $args] >= 2 } {
+	switch [dg-process-target [lindex $args 1]] {
+	    "S" { }
+	    "N" { return }
+	    "F" { setup_xfail "*-*-*" }
+	    "P" { }
+	}
+    }
+
+    # Find nm like we find g++ in g++.exp.
+    if ![info exists nm]  {
+	set nm [findfile $base_dir/../../../binutils/nm \
+		$base_dir/../../../binutils/nm \
+	        [findfile $base_dir/../../nm $base_dir/../../nm \
+		      [findfile $base_dir/nm $base_dir/nm \
+		       [transform nm]]]]
+	verbose -log "nm is $nm"
+    }
+
+    set output_file "[glob -nocomplain $output_file]"
+    if { $output_file == "" } {
+	fail "$scan_directive $args: output file does not exist"
+	return
+    }
+
+    set fd [open "| $nm $output_file" r]
+    set text [read $fd]
+    close $fd
+
+    if [regexp -- [lindex $args 0] $text] {
+	return 1
+    } else {
+	return 0
+    }
+}
+
+# Utility for scanning a symbol in the final executable, invoked via dg-final.
+# Call pass if pattern is present, otherwise fail.
+#
+# Argument 0 is the regexp to match.
+# Argument 1 handles expected failures and the like
+proc scan-symbol { args } {
+    set testcase [testname-for-summary]
+    if { [scan-symbol-common "scan-symbol" $args]} {
+	pass "$testcase   scan-symbol $args"
+    } else {
+	fail "$testcase   scan-symbol $args"
+    }
+}
+
+# Utility for scanning a symbol in the final executable, invoked via dg-final.
+# Call pass if pattern is absent, otherwise fail.
+#
+# Argument 0 is the regexp to match.
+# Argument 1 handles expected failures and the like
+proc scan-symbol-not { args } {
+    set testcase [testname-for-summary]
+    if { [scan-symbol-common "scan-symbol-not" $args]} {
+	fail "$testcase   scan-symbol-not $args"
+    } else {
+	pass "$testcase   scan-symbol-not $args"
+    }
+}
+
 set additional_prunes ""
 set dg_runtest_extra_prunes ""
diff --git a/gcc/testsuite/lib/lto.exp b/gcc/testsuite/lib/lto.exp
index 58a84aa1936..c2c35698827 100644
--- a/gcc/testsuite/lib/lto.exp
+++ b/gcc/testsuite/lib/lto.exp
@@ -712,6 +712,17 @@ proc lto-execute { src1 sid } {
 
 	# There's a unique name for each executable we generate.
 	set execname "${execbase}-${count}1.exe"
+
+	# The LTO tests don't use dg-test, so testname_with_flags and
+	# output_file need to be defined explicitly for each file.  scan-symbol
+	# directives rely on both of these to be defined to find the symbol to
+	# scan and for the text to print in the PASS/FAIL since they can also
+	# be called from dg-test.  testname_with_flags is also used via
+	# testname-for-summary when calling into generic function below to
+	# clean temporary files.
+	set output_file $execname
+	set testname_with_flags $execname
+
 	incr count
 
 	file_on_host delete $execname
@@ -774,11 +785,7 @@ proc lto-execute { src1 sid } {
 	    }
 	}
 
-	# Clean up after -save-temps.  The LTO tests don't use dg-test, so
-	# testname-for-summary needs to be defined explicitly for each
-	# file that needs to be removed.
-	set testname_with_flags $execname
-
+	# Clean up after -save-temps.
 	eval "cleanup-saved-temps"
 
 	for {set i 0} {$i < $num_srcs} {incr i} {
@@ -801,52 +808,6 @@ proc lto-execute { src1 sid } {
     }
 }
 
-# Utility for scanning a symbol in the final executable, invoked via dg-final.
-# Call pass if pattern is present, otherwise fail.
-#
-# Argument 0 is the regexp to match.
-# Argument 1 handles expected failures and the like
-proc scan-symbol { args } {
-    global nm
-    global base_dir
-    upvar 2 execname execname
-
-    if { [llength $args] >= 2 } {
-	switch [dg-process-target [lindex $args 1]] {
-	    "S" { }
-	    "N" { return }
-	    "F" { setup_xfail "*-*-*" }
-	    "P" { }
-	}
-    }
-
-    # Find nm like we find g++ in g++.exp.
-    if ![info exists nm]  {
-	set nm [findfile $base_dir/../../../binutils/nm \
-		$base_dir/../../../binutils/nm \
-	        [findfile $base_dir/../../nm $base_dir/../../nm \
-		      [findfile $base_dir/nm $base_dir/nm \
-		       [transform nm]]]]
-	verbose -log "nm is $nm"
-    }
-
-    set output_file "[glob -nocomplain $execname]"
-    if { $output_file == "" } {
-	fail "scan-symbol $args: dump file does not exist"
-	return
-    }
-
-    set fd [open "| $nm $output_file" r]
-    set text [read $fd]
-    close $fd
-
-    if [regexp -- [lindex $args 0] $text] {
-	pass "scan-symbol $args"
-    } else {
-	fail "scan-symbol $args"
-    }
-}
-
 # Call pass if object readelf is ok, otherwise fail.
 # example: /* { dg-final { object-readelf Tag_ABI_enum_size int} } */
 proc object-readelf { args } {
diff --git a/libgcc/config/arm/ieee754-df.S b/libgcc/config/arm/ieee754-df.S
index 480e33da31f..9f2ae9ed698 100644
--- a/libgcc/config/arm/ieee754-df.S
+++ b/libgcc/config/arm/ieee754-df.S
@@ -617,7 +617,18 @@ ARM_FUNC_ALIAS aeabi_l2d floatdidf
 
 #endif /* L_addsubdf3 */
 
-#ifdef L_arm_muldivdf3
+#if defined(L_arm_muldf3) || defined(L_arm_muldivdf3)
+
+@ Define multiplication as weak in _arm_muldf3.o so that it can be overriden
+@ by the global definition in _arm_muldivdf3.o.  This allows a program only
+@ using multiplication to take the weak definition which does not contain the
+@ division code. Programs using only division or both division and
+@ multiplication will pull _arm_muldivdf3.o from which both the multiplication
+@ and division are taken thanks to the override.
+#ifdef L_arm_muldf3
+WEAK muldf3
+WEAK aeabi_dmul
+#endif
 
 ARM_FUNC_START muldf3
 ARM_FUNC_ALIAS aeabi_dmul muldf3
@@ -719,6 +730,7 @@ LSYM(Lml_1):
 	orr	xh, xh, #0x00100000
 	mov	lr, #0
 	subs	r4, r4, #1
+
 LSYM(Lml_u):
 	@ Overflow?
 	bgt	LSYM(Lml_o)
@@ -870,6 +882,8 @@ LSYM(Lml_n):
 	FUNC_END aeabi_dmul
 	FUNC_END muldf3
 
+#ifdef L_arm_muldivdf3
+
 ARM_FUNC_START divdf3
 ARM_FUNC_ALIAS aeabi_ddiv divdf3
 	CFI_START_FUNCTION
@@ -1067,6 +1081,7 @@ LSYM(Ldv_s):
 	FUNC_END divdf3
 
 #endif /* L_muldivdf3 */
+#endif /* L_arm_muldf3 || L_arm_muldivdf3 */
 
 #ifdef L_arm_cmpdf2
 
diff --git a/libgcc/config/arm/ieee754-sf.S b/libgcc/config/arm/ieee754-sf.S
index 28e0d793281..0b4d1ab377d 100644
--- a/libgcc/config/arm/ieee754-sf.S
+++ b/libgcc/config/arm/ieee754-sf.S
@@ -428,7 +428,18 @@ ARM_FUNC_ALIAS aeabi_l2f floatdisf
 
 #endif /* L_addsubsf3 */
 
-#ifdef L_arm_muldivsf3
+#if defined(L_arm_mulsf3) || defined(L_arm_muldivsf3)
+
+@ Define multiplication as weak in _arm_mulsf3.o so that it can be overriden
+@ by the global definition in _arm_muldivsf3.o.  This allows a program only
+@ using multiplication to take the weak definition which does not contain the
+@ division code. Programs using only division or both division and
+@ multiplication will pull _arm_muldivsf3.o from which both the multiplication
+@ and division are taken thanks to the override.
+#ifdef L_arm_mulsf3
+WEAK mulsf3
+WEAK aeabi_fmul
+#endif
 
 ARM_FUNC_START mulsf3
 ARM_FUNC_ALIAS aeabi_fmul mulsf3
@@ -613,6 +624,8 @@ LSYM(Lml_n):
 	FUNC_END aeabi_fmul
 	FUNC_END mulsf3
 
+#ifdef L_arm_muldivsf3
+
 ARM_FUNC_START divsf3
 ARM_FUNC_ALIAS aeabi_fdiv divsf3
 	CFI_START_FUNCTION
@@ -756,6 +769,7 @@ LSYM(Ldv_s):
 	FUNC_END divsf3
 
 #endif /* L_muldivsf3 */
+#endif /* L_arm_mulsf3 || L_arm_muldivsf3 */
 
 #ifdef L_arm_cmpsf2
 
diff --git a/libgcc/config/arm/lib1funcs.S b/libgcc/config/arm/lib1funcs.S
index ff06d504a4c..193fb251fdb 100644
--- a/libgcc/config/arm/lib1funcs.S
+++ b/libgcc/config/arm/lib1funcs.S
@@ -359,12 +359,8 @@ SYM (\name):
 #define THUMB_SYNTAX
 #endif
 
-.macro FUNC_START name sp_section=
-  .ifc \sp_section, function_section
-	.section	.text.__\name,"ax",%progbits
-  .else
+.macro FUNC_START name
 	.text
-  .endif
 	.globl SYM (__\name)
 	TYPE (__\name)
 	.align 0
@@ -390,8 +386,8 @@ SYM (\name):
 #if defined(__thumb2__)
 
 /* For Thumb-2 we build everything in thumb mode.  */
-.macro ARM_FUNC_START name sp_section=
-       FUNC_START \name \sp_section
+.macro ARM_FUNC_START name
+       FUNC_START \name
        .syntax unified
 .endm
 #define EQUIV .thumb_set
@@ -422,12 +418,8 @@ _L__\name:
 #ifdef NOT_ISA_TARGET_32BIT
 #define EQUIV .thumb_set
 #else
-.macro	ARM_FUNC_START name sp_section=
-  .ifc \sp_section, function_section
-	.section	.text.__\name,"ax",%progbits
-  .else
+.macro	ARM_FUNC_START name
 	.text
-  .endif
 	.globl SYM (__\name)
 	TYPE (__\name)
 	.align 0
@@ -2169,7 +2161,8 @@ LSYM(Lchange_\register):
 .endm
 
 #ifndef __symbian__
-/* The condition here must match the one in gcc/config/arm/elf.h.  */
+/* The condition here must match the one in gcc/config/arm/elf.h and
+   libgcc/config/arm/t-elf.  */
 #ifndef NOT_ISA_TARGET_32BIT
 #include "ieee754-df.S"
 #include "ieee754-sf.S"
diff --git a/libgcc/config/arm/t-elf b/libgcc/config/arm/t-elf
index 9e7a3170f17..9da6cd37054 100644
--- a/libgcc/config/arm/t-elf
+++ b/libgcc/config/arm/t-elf
@@ -1,3 +1,19 @@
+ifeq (,$(findstring __symbian__,$(shell $(gcc_compile_bare) -dM -E - </dev/null)))
+
+ARM_ISA:=$(findstring __ARM_ARCH_ISA_ARM,$(shell $(gcc_compile_bare) -dM -E - </dev/null))
+THUMB1_ISA:=$(findstring __ARM_ARCH_ISA_THUMB 1,$(shell $(gcc_compile_bare) -dM -E - </dev/null))
+
+# The condition here must match the one in gcc/config/arm/elf.h and
+# libgcc/config/arm/lib1funcs.S.  _arm_muldf3 and _arm_mulsf3 must be included
+# first so that the weak multiplication symbols in the corresponding files are
+# chosen over the global symbols that _arm_muldivdf3 and _arm_muldivsf3
+# inclusion create when only multiplication is used, thus avoiding pulling in
+# useless division code.
+ifneq (__ARM_ARCH_ISA_THUMB 1,$(ARM_ISA)$(THUMB1_ISA))
+LIB1ASMFUNCS += _arm_muldf3 _arm_mulsf3
+endif
+endif # !__symbian__
+
 # For most CPUs we have an assembly soft-float implementations.
 # However this is not true for ARMv6M.  Here we want to use the soft-fp C
 # implementation.  The soft-fp code is only build for ARMv6M.  This pulls
-- 
2.19.1

