[PATCH] Avoid FROM being overwritten in expand_fix.

[liuhongt via Gcc-patches]

Hi:
  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.

  Boostrapped and regtested on x86_64-linux-gnu{-m32,}.
  Ok for trunk?

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.
---
 gcc/optabs.c                             | 10 +++++++---
 gcc/testsuite/gcc.target/i386/pr101282.c | 18 ++++++++++++++++++
 2 files changed, 25 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/i386/pr101282.c

diff --git a/gcc/optabs.c b/gcc/optabs.c
index ebed78fda3f..6af67d05253 100644
--- a/gcc/optabs.c
+++ b/gcc/optabs.c
@@ -5480,6 +5480,7 @@ expand_fix (rtx to, rtx from, int unsignedp)
     FOR_EACH_MODE_FROM (imode, GET_MODE (to))
       {
        int doing_unsigned = unsignedp;
+       rtx from1 = NULL_RTX;
 
        icode = can_fix_p (imode, fmode, unsignedp, &must_trunc);
        if (icode == CODE_FOR_nothing && imode != GET_MODE (to) && unsignedp)
@@ -5489,19 +5490,22 @@ expand_fix (rtx to, rtx from, int unsignedp)
          {
            rtx_insn *last = get_last_insn ();
            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,
+               from1 = expand_unop (GET_MODE (from), ftrunc_optab, from,
                                    temp, 0);
              }
 
            if (imode != GET_MODE (to))
              target = gen_reg_rtx (imode);
 
-           if (maybe_emit_unop_insn (icode, target, from,
+           if (!from1)
+             from1 = 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);
+}
-- 
2.27.0