| Message ID | 20240126050235.608008-1-quic_apinski@quicinc.com |
|---|---|
| State | New |
| Headers | show |
| Series | aarch64: Fix/avoid undefinedness in aarch64_classify_index [PR100212] | expand |
diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc index d2014ce1527..19c608bc3ed 100644 --- a/gcc/config/aarch64/aarch64.cc +++ b/gcc/config/aarch64/aarch64.cc @@ -10246,7 +10246,9 @@ aarch64_classify_index (struct aarch64_address_info *info, rtx x, type = ADDRESS_REG_UXTW; index = XEXP (XEXP (x, 0), 0); shift = exact_log2 (INTVAL (XEXP (XEXP (x, 0), 1))); - if (INTVAL (XEXP (x, 1)) != (HOST_WIDE_INT)0xffffffff << shift) + /* Avoid undefined code dealing with shift being -1. */ + if (shift != -1 + && INTVAL (XEXP (x, 1)) != (HOST_WIDE_INT)0xffffffff << shift) shift = -1; } /* (and:DI (ashift:DI (reg:DI) (const_int shift))
The problem here is we don't check the return value of exact_log2 and always use that result as shifter. This fixes the issue by avoiding the shift if the value was `-1` (which means the value was not exact a power of 2); in this case we could either check if the values was equal to -1 or not equal to because we then assign -1 to shift if the constant value was not equal. I chose `!=` as it seemed to be more obvious of what the code is doing. Committed as obvious after a build/test for aarch64-linux-gnu. gcc/ChangeLog: PR target/100212 * config/aarch64/aarch64.cc (aarch64_classify_index): Avoid undefined shift after the call to exact_log2. Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com> --- gcc/config/aarch64/aarch64.cc | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)