[PATCH] PR middle-end/88345: Honor -falign-functions=N even optimized for size.

[Kito Cheng <kito.cheng@sifive.com>]

From: Monk Chiang <monk.chiang@sifive.com>

Currnetly setting of -falign-functions=N will be ignored if the function
is optimized for size or marked as cold function.

However function alignment requirement is needed even optimized for
size in some situations, RISC-V target is an example, RISC-V kernel implement
patchable function that require function must be align to at least 4 bytes for
atomicly patch the function prologue.

Here is 4 way to fix that:
1. Fix -falign-functions=N, let it work as expect on -Os and all cold
functions, which is this patch.
2. Force align to 4 byte if -fpatchable-function-entry is given by adjust
RISC-V's FUNCTION_BOUNDARY.
3. Adjust RISC-V's FUNCTION_BOUNDARY to let it honor to -falign-functions=N.
4. Adding a -malign-functions=N for RISC-V...which x86 already deprecated that.

And this patch is the first approach.

gcc/ChangeLog:

	PR middle-end/88345
	* varasm.cc (assemble_start_function): Adjust function align
	even optimized for size.
	* doc/invoke.texi (Os): Remove -falign-functions= from the exclusion
	list of -Os.

gcc/testsuite/ChangeLog:

	PR middle-end/88345
	* gcc.target/i386/pr88345-1.c: New.
	* gcc.target/i386/pr88345-2.c: Ditto.
	* gcc.target/riscv/pr88345-1.c: Ditto.
	* gcc.target/riscv/pr88345-2.c: Ditto.
---
 gcc/doc/invoke.texi                        | 2 +-
 gcc/testsuite/gcc.target/i386/pr88345-1.c  | 5 +++++
 gcc/testsuite/gcc.target/i386/pr88345-2.c  | 5 +++++
 gcc/testsuite/gcc.target/riscv/pr88345-1.c | 5 +++++
 gcc/testsuite/gcc.target/riscv/pr88345-2.c | 5 +++++
 gcc/varasm.cc                              | 3 +--
 6 files changed, 22 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/i386/pr88345-1.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr88345-2.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/pr88345-1.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/pr88345-2.c

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index a2b0b9636f0..acf98c68825 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -11381,7 +11381,7 @@ results.  This is the default.
 Optimize for size.  @option{-Os} enables all @option{-O2} optimizations 
 except those that often increase code size:
 
-@gccoptlist{-falign-functions  -falign-jumps @gol
+@gccoptlist{-falign-jumps @gol
 -falign-labels  -falign-loops @gol
 -fprefetch-loop-arrays  -freorder-blocks-algorithm=stc}
 
diff --git a/gcc/testsuite/gcc.target/i386/pr88345-1.c b/gcc/testsuite/gcc.target/i386/pr88345-1.c
new file mode 100644
index 00000000000..226bb9ffc82
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr88345-1.c
@@ -0,0 +1,5 @@
+/* { dg-do compile } */
+/* { dg-options "-falign-functions=128" } */
+/* { dg-final { scan-assembler-times "\.p2align\t7" 1 } } */
+
+__attribute__((__cold__)) void a() {}
diff --git a/gcc/testsuite/gcc.target/i386/pr88345-2.c b/gcc/testsuite/gcc.target/i386/pr88345-2.c
new file mode 100644
index 00000000000..a7fc3b162dd
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr88345-2.c
@@ -0,0 +1,5 @@
+/* { dg-do compile } */
+/* { dg-options "-falign-functions=128 -Os" } */
+/* { dg-final { scan-assembler-times "\.p2align\t7" 1 } } */
+
+void a() {}
diff --git a/gcc/testsuite/gcc.target/riscv/pr88345-1.c b/gcc/testsuite/gcc.target/riscv/pr88345-1.c
new file mode 100644
index 00000000000..7d5afe683eb
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/pr88345-1.c
@@ -0,0 +1,5 @@
+/* { dg-do compile } */
+/* { dg-options "-falign-functions=128" } */
+/* { dg-final { scan-assembler-times "\.align\t7" 1 } } */
+
+__attribute__((__cold__)) void a() {}
diff --git a/gcc/testsuite/gcc.target/riscv/pr88345-2.c b/gcc/testsuite/gcc.target/riscv/pr88345-2.c
new file mode 100644
index 00000000000..d4fc89d86d8
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/pr88345-2.c
@@ -0,0 +1,5 @@
+/* { dg-do compile } */
+/* { dg-options "-falign-functions=128 -Os" } */
+/* { dg-final { scan-assembler-times "\.align\t7" 1 } } */
+
+void a() {}
diff --git a/gcc/varasm.cc b/gcc/varasm.cc
index 423f3f91af8..4001648b214 100644
--- a/gcc/varasm.cc
+++ b/gcc/varasm.cc
@@ -1923,8 +1923,7 @@ assemble_start_function (tree decl, const char *fnname)
      Note that we still need to align to DECL_ALIGN, as above,
      because ASM_OUTPUT_MAX_SKIP_ALIGN might not do any alignment at all.  */
   if (! DECL_USER_ALIGN (decl)
-      && align_functions.levels[0].log > align
-      && optimize_function_for_speed_p (cfun))
+      && align_functions.levels[0].log > align)
     {
 #ifdef ASM_OUTPUT_MAX_SKIP_ALIGN
       int align_log = align_functions.levels[0].log;
-- 
2.37.2