[gcc(refs/users/meissner/heads/work159)] PR target/112886, Add %S<n> to print_operand for vector pair support.

[Michael Meissner <meissner@gcc.gnu.org>]

https://gcc.gnu.org/g:142ffad93134ed8526d533ca83ea72b3d20cf752

commit 142ffad93134ed8526d533ca83ea72b3d20cf752
Author: Michael Meissner <meissner@linux.ibm.com>
Date:   Thu Feb 22 16:18:43 2024 -0500

    PR target/112886, Add %S<n> to print_operand for vector pair support.
    
    In looking at support for load vector pair and store vector pair for the
    PowerPC in GCC, I noticed that we were missing a print_operand output modifier
    if you are dealing with vector pairs to print the 2nd register in the vector
    pair.
    
    If the instruction inside of the asm used the Altivec encoding, then we could
    use the %L<n> modifier:
    
            __vector_pair *p, *q, *r;
            // ...
            __asm__ ("vaddudm %0,%1,%2\n\tvaddudm %L0,%L1,%L2"
                     : "=v" (*p)
                     : "v" (*q), "v" (*r));
    
    Likewise if we know the value to be in a tradiational FPR register, %L<n> will
    work for instructions that use the VSX encoding:
    
            __vector_pair *p, *q, *r;
            // ...
            __asm__ ("xvadddp %x0,%x1,%x2\n\txvadddp %L0,%L1,%L2"
                     : "=f" (*p)
                     : "f" (*q), "f" (*r));
    
    But if have a value that is in a traditional Altivec register, and the
    instruction uses the VSX encoding, %L<n> will a value between 0 and 31, when it
    should give a value between 32 and 63.
    
    This patch adds %S<n> that acts like %x<n>, except that it adds 1 to the
    register number.
    
    This is version 2 of the patch.  The only difference is I made the test case
    simpler to read.
    
    I have tested this on power10 and power9 little endian systems and on a power9
    big endian system.  There were no regressions in the patch.  Can I apply it to
    the trunk?
    
    It would be nice if I could apply it to the open branches.  Can I backport it
    after a burn-in period?
    
    2024-02-22  Michael Meissner  <meissner@linux.ibm.com>
    
    gcc/
    
            PR target/112886
            * config/rs6000/rs6000.cc (print_operand): Add %S<n> output modifier.
            * doc/md.texi (Modifiers): Mention %S can be used like %x.
    
    gcc/testsuite/
    
            PR target/112886
            * /gcc.target/powerpc/pr112886.c: New test.

Diff:
---
 gcc/config/rs6000/rs6000.cc                 | 10 +++++++---
 gcc/doc/md.texi                             |  5 +++--
 gcc/testsuite/gcc.target/powerpc/pr112886.c | 29 +++++++++++++++++++++++++++++
 3 files changed, 39 insertions(+), 5 deletions(-)

diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
index 9ecca93984f4..39ec1ed9ab67 100644
--- a/gcc/config/rs6000/rs6000.cc
+++ b/gcc/config/rs6000/rs6000.cc
@@ -14508,13 +14508,17 @@ print_operand (FILE *file, rtx x, int code)
 	print_operand (file, x, 0);
       return;
 
+    case 'S':
     case 'x':
-      /* X is a FPR or Altivec register used in a VSX context.  */
+      /* X is a FPR or Altivec register used in a VSX context.  %x<n> prints
+	 the VSX register number, %S<n> prints the 2nd register number for
+	 vector pair, decimal 128-bit floating and IBM 128-bit binary floating
+	 values.  */
       if (!REG_P (x) || !VSX_REGNO_P (REGNO (x)))
-	output_operand_lossage ("invalid %%x value");
+	output_operand_lossage ("invalid %%%c value", (code == 'S' ? 'S' : 'x'));
       else
 	{
-	  int reg = REGNO (x);
+	  int reg = REGNO (x) + (code == 'S' ? 1 : 0);
 	  int vsx_reg = (FP_REGNO_P (reg)
 			 ? reg - 32
 			 : reg - FIRST_ALTIVEC_REGNO + 32);
diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi
index 33b37e79cd4a..80b6b9c0af32 100644
--- a/gcc/doc/md.texi
+++ b/gcc/doc/md.texi
@@ -3386,8 +3386,9 @@ A VSX register (VSR), @code{vs0}@dots{}@code{vs63}.  This is either an
 FPR (@code{vs0}@dots{}@code{vs31} are @code{f0}@dots{}@code{f31}) or a VR
 (@code{vs32}@dots{}@code{vs63} are @code{v0}@dots{}@code{v31}).
 
-When using @code{wa}, you should use the @code{%x} output modifier, so that
-the correct register number is printed.  For example:
+When using @code{wa}, you should use either the @code{%x} or @code{%S}
+output modifier, so that the correct register number is printed.  For
+example:
 
 @smallexample
 asm ("xvadddp %x0,%x1,%x2"
diff --git a/gcc/testsuite/gcc.target/powerpc/pr112886.c b/gcc/testsuite/gcc.target/powerpc/pr112886.c
new file mode 100644
index 000000000000..4e59dcda6ea7
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pr112886.c
@@ -0,0 +1,29 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target power10_ok } */
+/* { dg-options "-mdejagnu-cpu=power10 -O2" } */
+
+/* PR target/112886: Test that print_operand %S<n> gives the correct register
+   number for VSX registers (i.e. if the register is an Altivec register, the
+   register number is 32..63 instead of 0..31.  */
+
+void
+test (__vector_pair *ptr1, __vector_pair *ptr2, __vector_pair *ptr3)
+{
+  register __vector_pair p asm ("vs10");
+  register __vector_pair q asm ("vs42");
+  register __vector_pair r asm ("vs44");
+
+  q = *ptr2;
+  r = *ptr3;
+
+  __asm__ ("xvadddp %x0,%x1,%x2\n\txvadddp %S0,%S1,%S2"
+	   : "=wa" (p)
+	   : "wa"  (q), "wa" (r));
+
+  *ptr1 = p;
+}
+
+/* { dg-final { scan-assembler-times {\mxvadddp 10,42,44\M} 1 } } */
+/* { dg-final { scan-assembler-times {\mxvadddp 11,43,45\M} 1 } } */
+/* { dg-final { scan-assembler-times {\mlxvpx?\M}           2 } } */
+/* { dg-final { scan-assembler-times {\mstxvpx?\M}          1 } } */