[gcc(refs/vendors/vrull/heads/for-upstream)] RISC-V: Use .p2align for code-alignment

[Philipp Tomsich]

https://gcc.gnu.org/g:4c3df1ee1d9f3f1bfbb8e2527b70f229beda0f1f

commit 4c3df1ee1d9f3f1bfbb8e2527b70f229beda0f1f
Author: Philipp Tomsich <philipp.tomsich@vrull.eu>
Date:   Wed Mar 16 22:28:11 2022 +0100

    RISC-V: Use .p2align for code-alignment
    
    RISC-V's .p2align (currently) ignores the max-skip argument.  As we
    have experimental patches underway to address this in a
    backwards-compatible manner, let's prepare GCC for the day when
    binutils gets updated.
    
    gcc/ChangeLog:
    
            * config/riscv/riscv.h (ASM_OUTPUT_MAX_SKIP_ALIGN): Implement.
    
    Series-to: gcc-patches@gcc.gnu.org
    Series-cc: Palmer Dabbelt <palmer@rivosinc.com>
    Series-cc: Vineet Gupta <vineetg@rivosinc.com>
    Series-cc: Christoph Muellner <christoph.muellner@vrull.eu>
    Series-cc: Kito Cheng <kito.cheng@gmail.com>
    Series-cc: Jeff Law <jlaw@ventanamicro.com>

Diff:
---
 gcc/config/riscv/riscv.h | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/gcc/config/riscv/riscv.h b/gcc/config/riscv/riscv.h
index 2d0d170645c3..c216173cf6ba 100644
--- a/gcc/config/riscv/riscv.h
+++ b/gcc/config/riscv/riscv.h
@@ -938,6 +938,24 @@ typedef struct {
   fprintf (STREAM, "\t.word\t%sL%d-%sL%d\n",				\
 	   LOCAL_LABEL_PREFIX, VALUE, LOCAL_LABEL_PREFIX, REL)
 
+#ifdef HAVE_GAS_MAX_SKIP_P2ALIGN
+/* Support for -falign-* switches.  Use .p2align to ensure that code
+   sections are padded with NOP instructions, rather than zeros.  */
+#define ASM_OUTPUT_MAX_SKIP_ALIGN(FILE, LOG, MAX_SKIP)		\
+  do								\
+    {								\
+      if ((LOG) != 0)						\
+	{							\
+	  if ((MAX_SKIP) == 0)					\
+	    fprintf ((FILE), "\t.p2align %d\n", (int) (LOG));	\
+	  else							\
+	    fprintf ((FILE), "\t.p2align %d,,%d\n",		\
+		     (int) (LOG), (int) (MAX_SKIP));		\
+	}							\
+    } while (0)
+
+#endif /* HAVE_GAS_MAX_SKIP_P2ALIGN */
+
 /* This is how to output an assembler line
    that says to advance the location counter
    to a multiple of 2**LOG bytes.  */