| Message ID | 87tx4lxctu.fsf@googlemail.com |
|---|---|
| State | New |
| Headers | show |
On September 6, 2014 12:28:29 PM CEST, Richard Sandiford <rdsandiford@googlemail.com> wrote: >This PR is about a case where an XOR+EQ sequence can legitimately >be simplified. The problem was that the sequence was operating on >vectors while the simplified version used a 0 CONST_INT (const0_rtx). > >The code seems to have been like that for a long time but presumably >the bug has been latent until now. I suppose normally we'd want >earlier optimisations to catch this. > >Tested on x86_64-linux-gnu. OK to install? OK. Thanks, Richard. >Thanks, >Richard > > >gcc/ > PR rtl-optimization/62208 > * simplify-rtx.c (simplify_relational_operation_1): Use CONST0_RTX > rather than const0_rtx in eq/ne-xor simplifications. > >gcc/testsuite/ > * gcc.target/i386/pr62208.c: New test. > >Index: gcc/simplify-rtx.c >=================================================================== >--- gcc/simplify-rtx.c 2014-09-06 11:05:20.859563557 +0100 >+++ gcc/simplify-rtx.c 2014-09-06 11:05:20.935564244 +0100 >@@ -4480,16 +4480,16 @@ simplify_relational_operation_1 (enum rt > && op0code == XOR > && rtx_equal_p (XEXP (op0, 0), op1) > && !side_effects_p (XEXP (op0, 0))) >- return simplify_gen_relational (code, mode, cmp_mode, >- XEXP (op0, 1), const0_rtx); >+ return simplify_gen_relational (code, mode, cmp_mode, XEXP (op0, >1), >+ CONST0_RTX (mode)); > > /* Likewise (eq/ne (xor x y) y) simplifies to (eq/ne x 0). */ > if ((code == EQ || code == NE) > && op0code == XOR > && rtx_equal_p (XEXP (op0, 1), op1) > && !side_effects_p (XEXP (op0, 1))) >- return simplify_gen_relational (code, mode, cmp_mode, >- XEXP (op0, 0), const0_rtx); >+ return simplify_gen_relational (code, mode, cmp_mode, XEXP (op0, >0), >+ CONST0_RTX (mode)); > > /* (eq/ne (xor x C1) C2) simplifies to (eq/ne x (C1^C2)). */ > if ((code == EQ || code == NE) >Index: gcc/testsuite/gcc.target/i386/pr62208.c >=================================================================== >--- /dev/null 2014-09-03 21:33:59.721983712 +0100 >+++ gcc/testsuite/gcc.target/i386/pr62208.c 2014-09-06 >11:09:18.220708443 +0100 >@@ -0,0 +1,23 @@ >+/* { dg-options "-O3 -fwhole-program -march=x86-64" } */ >+ >+int *a; >+unsigned int b; >+ >+void fn2 () >+{ >+ int t[9]; >+ for (; b; b++) >+ *a ^= (~t[b] != t[b]); >+} >+ >+int fn1 () >+{ >+ fn2 (); >+ return 0; >+} >+ >+int main () >+{ >+ fn1 (); >+ return 0; >+}
Index: gcc/simplify-rtx.c =================================================================== --- gcc/simplify-rtx.c 2014-09-06 11:05:20.859563557 +0100 +++ gcc/simplify-rtx.c 2014-09-06 11:05:20.935564244 +0100 @@ -4480,16 +4480,16 @@ simplify_relational_operation_1 (enum rt && op0code == XOR && rtx_equal_p (XEXP (op0, 0), op1) && !side_effects_p (XEXP (op0, 0))) - return simplify_gen_relational (code, mode, cmp_mode, - XEXP (op0, 1), const0_rtx); + return simplify_gen_relational (code, mode, cmp_mode, XEXP (op0, 1), + CONST0_RTX (mode)); /* Likewise (eq/ne (xor x y) y) simplifies to (eq/ne x 0). */ if ((code == EQ || code == NE) && op0code == XOR && rtx_equal_p (XEXP (op0, 1), op1) && !side_effects_p (XEXP (op0, 1))) - return simplify_gen_relational (code, mode, cmp_mode, - XEXP (op0, 0), const0_rtx); + return simplify_gen_relational (code, mode, cmp_mode, XEXP (op0, 0), + CONST0_RTX (mode)); /* (eq/ne (xor x C1) C2) simplifies to (eq/ne x (C1^C2)). */ if ((code == EQ || code == NE) Index: gcc/testsuite/gcc.target/i386/pr62208.c =================================================================== --- /dev/null 2014-09-03 21:33:59.721983712 +0100 +++ gcc/testsuite/gcc.target/i386/pr62208.c 2014-09-06 11:09:18.220708443 +0100 @@ -0,0 +1,23 @@ +/* { dg-options "-O3 -fwhole-program -march=x86-64" } */ + +int *a; +unsigned int b; + +void fn2 () +{ + int t[9]; + for (; b; b++) + *a ^= (~t[b] != t[b]); +} + +int fn1 () +{ + fn2 (); + return 0; +} + +int main () +{ + fn1 (); + return 0; +}