[gcc r12-3368] Avoid FROM being overwritten in expand_fix.

[hongtao Liu <liuhongt@gcc.gnu.org>]

https://gcc.gnu.org/g:93e6809459f34ca7b5928f1729246b2e9dfb3eb4

commit r12-3368-g93e6809459f34ca7b5928f1729246b2e9dfb3eb4
Author: liuhongt <hongtao.liu@intel.com>
Date:   Mon Sep 6 17:09:38 2021 +0800

    Avoid FROM being overwritten in expand_fix.
    
    For the conversion from _Float16 to int, if the corresponding optab
    does not exist, the compiler will try the wider mode (SFmode here),
    but when floatsfsi exists but FAIL, FROM will be rewritten, which
    leads to a PR runtime error.
    
    gcc/ChangeLog:
    
            PR middle-end/102182
            * optabs.c (expand_fix): Add from1 to avoid from being
            overwritten.
    
    gcc/testsuite/ChangeLog:
    
            PR middle-end/102182
            * gcc.target/i386/pr101282.c: New test.

Diff:
---
 gcc/optabs.c                             | 11 ++++++-----
 gcc/testsuite/gcc.target/i386/pr101282.c | 18 ++++++++++++++++++
 2 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/gcc/optabs.c b/gcc/optabs.c
index ebed78fda3f..019bbb62882 100644
--- a/gcc/optabs.c
+++ b/gcc/optabs.c
@@ -5488,20 +5488,21 @@ expand_fix (rtx to, rtx from, int unsignedp)
 	if (icode != CODE_FOR_nothing)
 	  {
 	    rtx_insn *last = get_last_insn ();
+	    rtx from1 = from;
 	    if (fmode != GET_MODE (from))
-	      from = convert_to_mode (fmode, from, 0);
+	      from1 = convert_to_mode (fmode, from, 0);
 
 	    if (must_trunc)
 	      {
-		rtx temp = gen_reg_rtx (GET_MODE (from));
-		from = expand_unop (GET_MODE (from), ftrunc_optab, from,
-				    temp, 0);
+		rtx temp = gen_reg_rtx (GET_MODE (from1));
+		from1 = expand_unop (GET_MODE (from1), ftrunc_optab, from1,
+				     temp, 0);
 	      }
 
 	    if (imode != GET_MODE (to))
 	      target = gen_reg_rtx (imode);
 
-	    if (maybe_emit_unop_insn (icode, target, from,
+	    if (maybe_emit_unop_insn (icode, target, from1,
 				      doing_unsigned ? UNSIGNED_FIX : FIX))
 	      {
 		if (target != to)
diff --git a/gcc/testsuite/gcc.target/i386/pr101282.c b/gcc/testsuite/gcc.target/i386/pr101282.c
new file mode 100644
index 00000000000..2148b9294ef
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr101282.c
@@ -0,0 +1,18 @@
+/* { dg-do run { target { ia32 } } } */
+/* { dg-options "-Os -march=i686 -mfpmath=sse -msse2" } */
+
+#include<stdlib.h>
+int
+main (void)
+{
+  static volatile unsigned int ivin, ivout;
+  static volatile _Float16 fv1, fv2;
+  ivin = ((unsigned int)1);
+  fv1 = ((unsigned int)1);
+  fv2 = ivin;
+  ivout = fv2;
+  if (ivout != ((unsigned int)1))
+    abort ();
+
+  exit (0);
+}