re PR rtl-optimization/64291 (Miscompile t-div in GMP's testsuite)

2014-12-18  Vladimir Makarov  <vmakarov@redhat.com>

	PR rtl-optimization/64291
	* lra-remat.c (bad_for_rematerialization_p): Add UNPSEC_VLOATILE.
	(create_cands): Process only output reload insn with potential
	cands.

2014-12-18  Vladimir Makarov  <vmakarov@redhat.com>

	PR rtl-optimization/64291
	* testsuite/gcc.target/i386/pr64291-[12].c: New tests.

From-SVN: r218874

gcc/ChangeLog

@@ -1,3 +1,10 @@
+2014-12-18  Vladimir Makarov  <vmakarov@redhat.com>
+
+	PR rtl-optimization/64291
+	* lra-remat.c (bad_for_rematerialization_p): Add UNPSEC_VLOATILE.
+	(create_cands): Process only output reload insn with potential
+	cands.
+
 2014-12-18  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* config/i386/i386.c (ix86_expand_call): Skip setting up RAX

gcc/lra-remat.c

@@ -350,12 +350,12 @@ finish_cand_table (void)
 
 
 
-/* Return true if X contains memory or UNSPEC.  We can not just check
+/* Return true if X contains memory or some UNSPEC.  We can not just
-   insn operands as memory or unspec might be not an operand itself
+   check insn operands as memory or unspec might be not an operand
-   but contain an operand.  Insn with memory access is not profitable
+   itself but contain an operand.  Insn with memory access is not
-   for rematerialization.  Rematerialization of UNSPEC might result in
+   profitable for rematerialization.  Rematerialization of UNSPEC
-   wrong code generation as the UNPEC effect is unknown
+   might result in wrong code generation as the UNPEC effect is
-   (e.g. generating a label).  */
+   unknown (e.g. generating a label).  */
 static bool
 bad_for_rematerialization_p (rtx x)
 {
@@ -363,7 +363,7 @@ bad_for_rematerialization_p (rtx x)
   const char *fmt;
   enum rtx_code code;
 
-  if (MEM_P (x) || GET_CODE (x) == UNSPEC)
+  if (MEM_P (x) || GET_CODE (x) == UNSPEC || GET_CODE (x) == UNSPEC_VOLATILE)
     return true;
   code = GET_CODE (x);
   fmt = GET_RTX_FORMAT (code);
@@ -406,7 +406,7 @@ operand_to_remat (rtx_insn *insn)
     if (reg->regno == STACK_POINTER_REGNUM && frame_pointer_needed)
       return -1;
     else if (reg->type == OP_OUT && ! reg->subreg_p
-	&& find_regno_note (insn, REG_UNUSED, reg->regno) == NULL)
+	     && find_regno_note (insn, REG_UNUSED, reg->regno) == NULL)
       {
 	/* We permits only one spilled reg.  */
 	if (found_reg != NULL)
@@ -508,11 +508,14 @@ create_cands (void)
 
 	if ((set = single_set (insn)) != NULL
 	    && REG_P (SET_SRC (set)) && REG_P (SET_DEST (set))
-	    && (src_regno = REGNO (SET_SRC (set))) >= FIRST_PSEUDO_REGISTER
+	    && ((src_regno = REGNO (SET_SRC (set)))
+		>= lra_constraint_new_regno_start)
 	    && (dst_regno = REGNO (SET_DEST (set))) >= FIRST_PSEUDO_REGISTER
 	    && reg_renumber[dst_regno] < 0
 	    && (insn2 = regno_potential_cand[src_regno].insn) != NULL
 	    && BLOCK_FOR_INSN (insn2) == BLOCK_FOR_INSN (insn))
+	  /* It is an output reload insn after insn can be
+	     rematerialized (potential candidate).  */
 	  create_cand (insn2, regno_potential_cand[src_regno].nop, dst_regno);
 	if (nop < 0)
 	  goto fail;

gcc/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2014-12-18  Vladimir Makarov  <vmakarov@redhat.com>
+
+	PR rtl-optimization/64291
+	* testsuite/gcc.target/i386/pr64291-[12].c: New tests.
+
 2014-12-18  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/60955

gcc/testsuite/gcc.target/i386/pr64291-1.c

@@ -0,0 +1,51 @@
+/* { dg-options "-O2" } */
+/* { dg-additional-sources pr64291-2.c } */
+/* { dg-do run } */
+void f(void*,...);
+void g(void*,long,long);
+int nnn=0;
+long test=0;
+
+typedef struct
+{
+  int _mp_size;
+  unsigned long *_mp_d;
+} __mpz_struct;
+typedef __mpz_struct mpz_t[1];
+
+int main ()
+{
+  mpz_t n, d;
+  long nn, dn;
+  unsigned long *np, *dup, *dnp, *qp;
+  long alloc, itch;
+
+  f (n);
+  f (d);
+  qp = (unsigned long*)__builtin_alloca(4099*8) + 1;
+  dnp = (unsigned long*)__builtin_alloca (2049*8);
+  alloc = 1;
+  for (test = 0; test < 1; test++)
+    {
+      dn = d->_mp_size;
+      dup = d->_mp_d;
+      f (dnp, dup, dn);
+      dnp[dn - 1] |= 1UL<<63;
+      f (0);
+      nn = nnn;
+      np = n->_mp_d;
+      qp[-1] = -757136820;
+      qp[nn - dn + 1] = 14883681;
+      f (0);
+      if (dn >= 6)
+	f (0);
+      itch = nn + 1;
+      if (itch + 1> alloc)
+	{
+	  g(0,alloc*8,(itch+1)*8);
+	  alloc = itch + 1;
+	}
+      f (np, nn);
+    }
+  return 0;
+}

gcc/testsuite/gcc.target/i386/pr64291-2.c

@@ -0,0 +1,4 @@
+/* { dg-do compile } */
+extern void abort (void);
+void f(void*p,...){}
+void g(void*p,long a,long b){if (a!=8) abort();}