[TableGen] Allow shift operators to take bits<n>
Convert the operand to int if possible, i.e. if the value is properly
initialized. (I suppose there is further room for improvement here to also
peform the shift if the uninitialized bits are shifted out.)
With this little change we can now compute the scaling factor for compressed
displacement with pure tablegen code in the X86 backend. This is useful
because both the X86-disassembler-specific part of tablegen and the assembler
need this and TD is the natural sharing place.
The patch also adds the missing documentation for the shift and add operator.
llvm-svn: 213277
diff --git a/llvm/docs/TableGen/LangIntro.rst b/llvm/docs/TableGen/LangIntro.rst
index 3e74dff..0f8b3f6 100644
--- a/llvm/docs/TableGen/LangIntro.rst
+++ b/llvm/docs/TableGen/LangIntro.rst
@@ -208,6 +208,12 @@
on string, int and bit objects. Use !cast<string> to compare other types of
objects.
+``!shl(a,b)``
+``!srl(a,b)``
+``!sra(a,b)``
+``!add(a,b)``
+ The usual logical and arithmetic operators.
+
Note that all of the values have rules specifying how they convert to values
for different types. These rules allow you to assign a value like "``7``"
to a "``bits<4>``" value, for example.