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Diffstat (limited to 'tcg/README')
| -rw-r--r-- | tcg/README | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/tcg/README b/tcg/README index 7e7c06b41c..bdb44dfd3b 100644 --- a/tcg/README +++ b/tcg/README @@ -390,6 +390,11 @@ GCC like constraints are used to define the constraints of every instruction. Memory constraints are not supported in this version. Aliases are specified in the input operands as for GCC. +The same register may be used for both an input and an output, even when +they are not explicitly aliased. If an op expands to multiple target +instructions then care must be taken to avoid clobbering input values. +GCC style "early clobber" outputs are not currently supported. + A target can define specific register or constant constraints. If an operation uses a constant input constraint which does not allow all constants, it must also accept registers in order to have a fallback. |