[PATCH] rtl-optimization: ppc backend generates unnecessary signed extension.

[Ajit Agarwal via Gcc-patches]

Hello All:

This patch removed unnecessary signed extension elimination in ree pass.
Bootstrapped and regtested on powerpc64-linux-gnu.


Thanks & Regards
Ajit

        rtl-optimization: ppc backend generates unnecessary signed extension.

        Eliminate unnecessary redundant signed extension.

        2023-03-23  Ajit Kumar Agarwal  <aagar...@linux.ibm.com>

gcc/ChangeLog:

        * ree.cc: Modification for  AND opcode support to eliminate
        unnecessary signed extension.
        * testsuite/g++.target/powerpc/sext-elim.C: New tests.
---
 gcc/ree.cc                                   | 24 +++++++++++++++++---
 gcc/testsuite/g++.target/powerpc/sext-elim.C | 19 ++++++++++++++++
 2 files changed, 40 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/g++.target/powerpc/sext-elim.C

diff --git a/gcc/ree.cc b/gcc/ree.cc
index d09f55149b1..63d8cf9f237 100644
--- a/gcc/ree.cc
+++ b/gcc/ree.cc
@@ -364,6 +364,7 @@ combine_set_extension (ext_cand *cand, rtx_insn *curr_insn, 
rtx *orig_set)
       rtx simplified_temp_extension = simplify_rtx (temp_extension);
       if (simplified_temp_extension)
         temp_extension = simplified_temp_extension;
+
       new_set = gen_rtx_SET (new_reg, temp_extension);
     }
   else if (GET_CODE (orig_src) == IF_THEN_ELSE)
@@ -375,11 +376,21 @@ combine_set_extension (ext_cand *cand, rtx_insn 
*curr_insn, rtx *orig_set)
   else
     {
       /* This is the normal case.  */
-      rtx temp_extension
-       = gen_rtx_fmt_e (cand->code, cand->mode, orig_src);
+      rtx temp_extension = NULL_RTX;
+
+      if (GET_CODE (SET_SRC (cand_pat)) == AND)
+       temp_extension
+       = gen_rtx_fmt_ee (cand->code, cand->mode,orig_src,
+                         XEXP (SET_SRC (cand_pat), 1));
+      else
+       temp_extension
+       = gen_rtx_fmt_e (cand->code, cand->mode,orig_src);
+
       rtx simplified_temp_extension = simplify_rtx (temp_extension);
+
       if (simplified_temp_extension)
         temp_extension = simplified_temp_extension;
+
       new_set = gen_rtx_SET (new_reg, temp_extension);
     }
 
@@ -1047,7 +1058,14 @@ combine_reaching_defs (ext_cand *cand, const_rtx 
set_pat, ext_state *state)
         cannot be merged, we entirely give up.  In the future, we should allow
         extensions to be partially eliminated along those paths where the
         definitions could be merged.  */
-      if (apply_change_group ())
+       int num_clobbers = 0;
+       int icode = recog (cand->insn, cand->insn,
+                         (GET_CODE (cand->expr) == SET
+                          && ! reload_completed
+                          && ! reload_in_progress)
+                          ? &num_clobbers : 0);
+
+      if (apply_change_group () || (icode < 0))
         {
           if (dump_file)
             fprintf (dump_file, "All merges were successful.\n");
diff --git a/gcc/testsuite/g++.target/powerpc/sext-elim.C 
b/gcc/testsuite/g++.target/powerpc/sext-elim.C
new file mode 100644
index 00000000000..1180b9ce268
--- /dev/null
+++ b/gcc/testsuite/g++.target/powerpc/sext-elim.C
@@ -0,0 +1,19 @@
+/* { dg-do compile { target { powerpc*-*-* } } } */
+/* { dg-require-effective-target lp64 } */
+/* { dg-require-effective-target powerpc_p9vector_ok } */
+/* { dg-options "-mcpu=power9 -O2 -free" } */
+
+unsigned long c2l(unsigned char* p)
+{
+  unsigned long res = *p + *(p+1);
+  return res;
+}
+
+long c2sl(signed char* p)
+{
+  long res = *p + *(p+1);
+  return res;
+}
+
+/* { dg-final { scan-assembler-not "rldicl" } } */
+/* { dg-final { scan-assembler-not "extsw" } } */
-- 
2.31.1