On October 14, 2015 8:27:31 PM GMT+02:00, Marek Polacek <pola...@redhat.com> wrote: >Evidently, the X - (X / Y) * Y -> X % Y pattern can't change the >signedness of X from signed to unsigned, otherwise we'd generate >wrong code. (But unsigned -> signed should be fine.) > >Does anyone see a better fix than this? > >Bootstrapped/regtested on x86_64-linux, ok for trunk?
OK. Thanks, Richard. >2015-10-14 Marek Polacek <pola...@redhat.com> > > PR tree-optimization/67953 > * match.pd (X - (X / Y) * Y): Don't change signedness of @0. > > * gcc.dg/fold-minus-6.c (fn4): Change the type of A to > unsigned. > * gcc.dg/torture/pr67953.c: New test. > >diff --git gcc/match.pd gcc/match.pd >index 655c9ff..24e19a9 100644 >--- gcc/match.pd >+++ gcc/match.pd >@@ -267,7 +267,8 @@ along with GCC; see the file COPYING3. If not see > /* X - (X / Y) * Y is the same as X % Y. */ > (simplify > (minus (convert1? @0) (convert2? (mult (trunc_div @0 @1) @1))) >- (if (INTEGRAL_TYPE_P (type) || VECTOR_INTEGER_TYPE_P (type)) >+ (if ((INTEGRAL_TYPE_P (type) || VECTOR_INTEGER_TYPE_P (type)) >+ && TYPE_UNSIGNED (TREE_TYPE (@0)) == TYPE_UNSIGNED (type)) > (trunc_mod (convert @0) (convert @1)))) > > /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR, >diff --git gcc/testsuite/gcc.dg/fold-minus-6.c >gcc/testsuite/gcc.dg/fold-minus-6.c >index 1c22c25..1535452 100644 >--- gcc/testsuite/gcc.dg/fold-minus-6.c >+++ gcc/testsuite/gcc.dg/fold-minus-6.c >@@ -20,7 +20,7 @@ fn3 (long int x) > } > > int >-fn4 (int a, int b) >+fn4 (unsigned int a, int b) > { > return a - (unsigned) ((a / b) * b); > } >diff --git gcc/testsuite/gcc.dg/torture/pr67953.c >gcc/testsuite/gcc.dg/torture/pr67953.c >index e69de29..5ce399b 100644 >--- gcc/testsuite/gcc.dg/torture/pr67953.c >+++ gcc/testsuite/gcc.dg/torture/pr67953.c >@@ -0,0 +1,42 @@ >+/* PR tree-optimization/67953 */ >+/* { dg-do run } */ >+ >+unsigned int >+fn1 (signed int a) >+{ >+ return (unsigned int) a - ((a / 3) * 3); >+} >+ >+unsigned int >+fn2 (signed int a) >+{ >+ return a - ((a / 3) * 3); >+} >+ >+unsigned int >+fn3 (int a) >+{ >+ return a - (unsigned) ((a / 3) * 3); >+} >+ >+signed int >+fn4 (int a) >+{ >+ return (unsigned) a - (unsigned) ((a / 3) * 3); >+} >+ >+signed int >+fn5 (unsigned int a) >+{ >+ return (signed) a - (int) ((a / 3) * 3); >+} >+ >+int >+main () >+{ >+ if (fn1 (-5) != -2 >+ || fn2 (-5) != -2 >+ || fn3 (-5) != -2 >+ || fn4 (-5) != -2) >+ __builtin_abort (); >+} > > Marek