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re PR rtl-optimization/88253 (Inlining of function incorrectly deletes volatile register access when using XOR in avr-gcc)

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Fix PR 88253

gcc/ChangeLog:

	PR rtl-optimization/88253
	* combine.c (combine_simplify_rtx): Test for side-effects before
	substituting by zero.

gcc/testsuite/ChangeLog:

	PR rtl-optimization/88253
	* gcc.target/avr/pr88253.c: New test.

From-SVN: r267198
This commit is contained in:
Senthil Kumar Selvaraj 2018-12-17 10:50:54 +00:00 committed by Senthil Kumar Selvaraj
parent 13e08dc939
commit d7c0082636
4 changed files with 30 additions and 2 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2018-12-17 Senthil Kumar Selvaraj <senthilkumar.selvaraj@microchip.com>
PR rtl-optimization/88253
* combine.c (combine_simplify_rtx): Test for side-effects before
substituting by zero.
2018-12-17 Richard Sandiford <richard.sandiford@arm.com>
* doc/invoke.texi (-fversion-loops-for-strides): Document

5
gcc/combine.c
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@ -5978,8 +5978,9 @@ combine_simplify_rtx (rtx x, machine_mode op0_mode, int in_dest,
&& known_eq (subreg_lowpart_offset (int_mode, int_op0_mode),
SUBREG_BYTE (x))
&& HWI_COMPUTABLE_MODE_P (int_op0_mode)
&& (nonzero_bits (SUBREG_REG (x), int_op0_mode)
& GET_MODE_MASK (int_mode)) == 0)
&& ((nonzero_bits (SUBREG_REG (x), int_op0_mode)
& GET_MODE_MASK (int_mode)) == 0)
&& !side_effects_p (SUBREG_REG (x)))
return CONST0_RTX (int_mode);
}

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2018-12-17 Senthil Kumar Selvaraj <senthilkumar.selvaraj@microchip.com>
PR rtl-optimization/88253
* gcc.target/avr/pr88253.c: New test.
2018-12-17 Richard Sandiford <richard.sandiford@arm.com>
* gcc.dg/loop-versioning-1.c: New test.

16
gcc/testsuite/gcc.target/avr/pr88253.c Normal file
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@ -0,0 +1,16 @@
/* { dg-do compile } */
/* { dg-options "-Os -w" } */
static int aRead() __attribute__((always_inline));
static int aRead() {
unsigned char h,l;
l = (*(volatile unsigned char *)(0x78)) ;
h = (*(volatile unsigned char *)(0x79)) ;
return (h<<8) | l;
}
int main() {
volatile unsigned char x;
x = aRead()^42;
}
/* { dg-final { scan-assembler "lds r\\d+,121" } } */