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[PATCH] Fix PR43438
- From: Richard Guenther <rguenther at suse dot de>
- To: gcc-patches at gcc dot gnu dot org
- Date: Fri, 19 Mar 2010 13:47:27 +0100 (CET)
- Subject: [PATCH] Fix PR43438
This fixes PR43438 where combine manages to drop a required
zero-extension. It is make_extraction that upon simplification to
a CONST_INT fails to zero-/sign-extend its value before returning
it. I also fail to see how it handles pos == BITS_PER_WORD.
Is there more proper RTL infrastructure to do this zero-/sign-extension
available? I couldn't find anything not operating on modes.
Thanks,
Richard.
2010-03-19 Richard Guenther <rguenther@suse.de>
PR rtl-optimization/43438
* combine.c (make_extraction): Properly zero-/sign-extend an
extraction of the low part of a CONST_INT.
* gcc.c-torture/execute/pr43438.c: New testcase.
Index: gcc/combine.c
===================================================================
*** gcc/combine.c (revision 157561)
--- gcc/combine.c (working copy)
*************** make_extraction (enum machine_mode mode,
*** 6793,6800 ****
if (mode == tmode)
return new_rtx;
! if (CONST_INT_P (new_rtx))
! return gen_int_mode (INTVAL (new_rtx), mode);
/* If we know that no extraneous bits are set, and that the high
bit is not set, convert the extraction to the cheaper of
--- 6793,6808 ----
if (mode == tmode)
return new_rtx;
! if (CONST_INT_P (new_rtx)
! && pos == 0)
! {
! double_int res;
! if (unsignedp)
! res = double_int_zext (shwi_to_double_int (INTVAL (new_rtx)), len);
! else
! res = double_int_sext (shwi_to_double_int (INTVAL (new_rtx)), len);
! return gen_int_mode (res.low, mode);
! }
/* If we know that no extraneous bits are set, and that the high
bit is not set, convert the extraction to the cheaper of
Index: gcc/testsuite/gcc.c-torture/execute/pr43438.c
===================================================================
*** gcc/testsuite/gcc.c-torture/execute/pr43438.c (revision 0)
--- gcc/testsuite/gcc.c-torture/execute/pr43438.c (revision 0)
***************
*** 0 ****
--- 1,23 ----
+ extern void abort (void);
+
+ static unsigned char g_2 = 1;
+ static int g_9;
+ static int *l_8 = &g_9;
+
+ static void func_12(int p_13)
+ {
+ int * l_17 = &g_9;
+ *l_17 &= 0 < p_13;
+ }
+
+ int main(void)
+ {
+ unsigned char l_11 = 254;
+ *l_8 |= g_2;
+ l_11 |= *l_8;
+ func_12(l_11);
+ if (g_9 != 1)
+ abort ();
+ return 0;
+ }
+