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aarch64: Fix status return logic in RNG intrinsics

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There is a bug with the RNG intrinsics in their return code. The definition says:

"Stores a 64-bit random number into the object pointed to by the argument and returns zero.
If the implementation could not generate a random number within a reasonable period of time
the object pointed to by the input is set to zero and a non-zero value is returned."

This means we should be testing whether to return non-zero with:
CSET W0, EQ
rather than NE.

This patch fixes that.

gcc/ChangeLog:

	* config/aarch64/aarch64-builtins.c (aarch64_expand_rng_builtin): Use EQ
	to compare against CC_REG rather than NE.

gcc/testsuite/ChangeLog:

	* gcc.target/aarch64/acle/rng_2.c: New test.
This commit is contained in:
Kyrylo Tkachov 2021-03-17 18:21:05 +00:00
parent adf14bdbc1
commit f7581eb38e
2 changed files with 13 additions and 1 deletions
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2
gcc/config/aarch64/aarch64-builtins.c
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@ -1954,7 +1954,7 @@ aarch64_expand_rng_builtin (tree exp, rtx target, int fcode, int ignore)
return target;
rtx cc_reg = gen_rtx_REG (CC_Zmode, CC_REGNUM);
rtx cmp_rtx = gen_rtx_fmt_ee (NE, SImode, cc_reg, const0_rtx);
rtx cmp_rtx = gen_rtx_fmt_ee (EQ, SImode, cc_reg, const0_rtx);
emit_insn (gen_aarch64_cstoresi (target, cmp_rtx, cc_reg));
return target;
}

12
gcc/testsuite/gcc.target/aarch64/acle/rng_2.c Normal file
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@ -0,0 +1,12 @@
/* { dg-do compile } */
/* { dg-options "-O2 -march=armv8.5-a+rng" } */
#include <arm_acle.h>
int test_rndr (uint64_t *addr)
{
return __rndr (addr);
}
/* { dg-final { scan-assembler-times {cset\t...?, eq} 1 } } */