[PATCH] Fix gimple-ssa-sprintf.c ICE (PR tree-optimization/83198)

[Jakub Jelinek]

Hi!

This patch fixes 2 issues in format_floating.  One is that when determining
precision, we should consider solely the type *printf* will read the
argument as (i.e. double unless L or ll modifier is used, in which case
long double), not the type of the argument, because the corresponding
argument could have any type, even not floating, or say __float128 etc.

This is fixed in the first 2 hunks.

The last hunk is to treat REAL_CSTs arguments of incompatible types
as unknown argument, we really don't know what say __float128 passed to
%f or double passed to %La will do; that is something diagnosed by -Wformat,
so the patch just treats it as arbitrary value of the type.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2017-12-13  Jakub Jelinek  <ja...@redhat.com>

        PR tree-optimization/83198
        * gimple-ssa-sprintf.c (format_floating): Set type solely based on
        dir.modifier, regardless of TREE_TYPE (arg).  Assume non-REAL_CST
        value if arg is a REAL_CST with incompatible type.

        * gcc.dg/pr83198.c: New test.

--- gcc/gimple-ssa-sprintf.c.jj 2017-11-03 15:37:04.000000000 +0100
+++ gcc/gimple-ssa-sprintf.c    2017-12-13 13:37:59.289435623 +0100
@@ -1885,6 +1885,8 @@ static fmtresult
 format_floating (const directive &dir, tree arg)
 {
   HOST_WIDE_INT prec[] = { dir.prec[0], dir.prec[1] };
+  tree type = (dir.modifier == FMT_LEN_L || dir.modifier == FMT_LEN_ll
+              ? long_double_type_node : double_type_node);
 
   /* For an indeterminate precision the lower bound must be assumed
      to be zero.  */
@@ -1892,10 +1894,6 @@ format_floating (const directive &dir, t
     {
       /* Get the number of fractional decimal digits needed to represent
         the argument without a loss of accuracy.  */
-      tree type = arg ? TREE_TYPE (arg) :
-       (dir.modifier == FMT_LEN_L || dir.modifier == FMT_LEN_ll
-        ? long_double_type_node : double_type_node);
-
       unsigned fmtprec
        = REAL_MODE_FORMAT (TYPE_MODE (type))->p;
 
@@ -1946,7 +1944,9 @@ format_floating (const directive &dir, t
        }
     }
 
-  if (!arg || TREE_CODE (arg) != REAL_CST)
+  if (!arg
+      || TREE_CODE (arg) != REAL_CST
+      || !useless_type_conversion_p (type, TREE_TYPE (arg)))
     return format_floating (dir, prec);
 
   /* The minimum and maximum number of bytes produced by the directive.  */
--- gcc/testsuite/gcc.dg/pr83198.c.jj   2017-12-13 13:43:36.056192309 +0100
+++ gcc/testsuite/gcc.dg/pr83198.c      2017-12-13 13:47:11.716474956 +0100
@@ -0,0 +1,18 @@
+/* PR tree-optimization/83198 */
+/* { dg-do compile } */
+/* { dg-options "-Wall -Wno-format" } */
+
+int
+foo (char *d[6], int x)
+{
+  int r = 0;
+  r += __builtin_sprintf (d[0], "%f", x);
+  r += __builtin_sprintf (d[1], "%a", x);
+  r += __builtin_sprintf (d[2], "%f", "foo");
+  r += __builtin_sprintf (d[3], "%a", "bar");
+#ifdef __SIZEOF_FLOAT128__
+  r += __builtin_sprintf (d[4], "%a", 1.0Q);
+  r += __builtin_sprintf (d[5], "%Lf", 1.0Q);
+#endif
+  return r;
+}

        Jakub