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| -rw-r--r-- | src/machine.tex | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/src/machine.tex b/src/machine.tex index be3413e..302a620 100644 --- a/src/machine.tex +++ b/src/machine.tex @@ -658,6 +658,8 @@ Whenever XLEN in any mode is set to a value less than the widest supported XLEN, all operations must ignore source operand register bits above the configured XLEN, and must sign-extend results to fill the entire widest supported XLEN in the destination register. +Similarly, {\tt pc} bits above XLEN are ignored, and when the {\tt pc} +is written, it is sign-extended to fill the widest supported XLEN. \begin{commentary} We require that operations always fill the entire underlying hardware registers with defined values to avoid implementation-defined |