From 7cb6668a1f251a35f26875398992eb4b1ae78f30 Mon Sep 17 00:00:00 2001 From: Meador Inge Date: Fri, 18 May 2012 09:04:38 +0000 Subject: [PATCH] re PR rtl-optimization/53352 (Incorrect CSE optimization on RTL expressions with a paradoxical subreg) gcc/ 2012-05-15 Meador Inge PR rtl-optimization/53352 * cse.c (equiv_constant): Ignore paradoxical subregs. gcc/testsuite/ 2012-05-15 Meador Inge PR rtl-optimization/53352 * gcc.dg/pr53352.c: New test. From-SVN: r187648 --- gcc/ChangeLog | 5 +++++ gcc/cse.c | 6 ++++- gcc/testsuite/ChangeLog | 5 +++++ gcc/testsuite/gcc.dg/pr53352.c | 41 ++++++++++++++++++++++++++++++++++ 4 files changed, 56 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/gcc.dg/pr53352.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 320ae0d09cca..ea1941e17b90 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2012-05-18 Meador Inge + + PR rtl-optimization/53352 + * cse.c (equiv_constant): Ignore paradoxical subregs. + 2012-05-17 Steven Bosscher PR rtl-optimization/53125 diff --git a/gcc/cse.c b/gcc/cse.c index 0ad7b2e2a46c..9f4e97932eda 100644 --- a/gcc/cse.c +++ b/gcc/cse.c @@ -3786,8 +3786,12 @@ equiv_constant (rtx x) } } - /* Otherwise see if we already have a constant for the inner REG. */ + /* Otherwise see if we already have a constant for the inner REG, + and if that is enough to calculate an equivalent constant for + the subreg. Note that the upper bits of paradoxical subregs + are undefined, so they cannot be said to equal anything. */ if (REG_P (SUBREG_REG (x)) + && GET_MODE_SIZE (mode) <= GET_MODE_SIZE (imode) && (new_rtx = equiv_constant (SUBREG_REG (x))) != 0) return simplify_subreg (mode, new_rtx, imode, SUBREG_BYTE (x)); diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 22f2982bbab2..64a011c0e876 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2012-05-18 Meador Inge + + PR rtl-optimization/53352 + * gcc.dg/pr53352.c: New test. + 2012-05-17 David S. Miller * gfortran.dg/bessel_7.f90: Bump allowed precision to avoid diff --git a/gcc/testsuite/gcc.dg/pr53352.c b/gcc/testsuite/gcc.dg/pr53352.c new file mode 100644 index 000000000000..1d2edf8bb8c8 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr53352.c @@ -0,0 +1,41 @@ +/* { dg-do run } */ +/* { dg-options "-O1" } */ + +#include + +typedef union +{ + struct + { + unsigned char a; + unsigned char b; + unsigned char c; + unsigned char d; + } parts; + unsigned long whole; +} T; + +T *g_t; + +void bar (unsigned long x) +{ + if (x != 0) + abort (); +} + +int main () +{ + T one; + T two; + T tmp1, tmp2; + + one.whole = 0xFFE0E0E0UL; + two.whole = 0xFF000000UL; + tmp1.parts = two.parts; + tmp2.parts = one.parts; + tmp2.parts.c = tmp1.parts.c; + one.parts = tmp2.parts; + + g_t = &one; + bar (0); +} -- 2.47.2