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[TableGen] Allow shift operators to take bits<n>

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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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213277 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Adam Nemet 2014-07-17 17:04:27 +00:00
parent 07bc0b6ae6
commit 30cced119b
3 changed files with 20 additions and 2 deletions
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6
docs/TableGen/LangIntro.rst
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@ -208,6 +208,12 @@ supported include:
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.

6
lib/TableGen/Record.cpp
View File

@ -955,8 +955,10 @@ Init *BinOpInit::Fold(Record *CurRec, MultiClass *CurMultiClass) const {
case SHL:
case SRA:
case SRL: {
IntInit *LHSi = dyn_cast<IntInit>(LHS);
IntInit *RHSi = dyn_cast<IntInit>(RHS);
IntInit *LHSi =
dyn_cast_or_null<IntInit>(LHS->convertInitializerTo(IntRecTy::get()));
IntInit *RHSi =
dyn_cast_or_null<IntInit>(RHS->convertInitializerTo(IntRecTy::get()));
if (LHSi && RHSi) {
int64_t LHSv = LHSi->getValue(), RHSv = RHSi->getValue();
int64_t Result;

10
test/TableGen/math.td
View File

@ -1,6 +1,16 @@
// RUN: llvm-tblgen %s | FileCheck %s
// XFAIL: vg_leak
def shifts {
bits<2> b = 0b10;
int i = 2;
int shifted_b = !shl(b, 2);
int shifted_i = !shl(i, 2);
}
// CHECK: def shifts
// CHECK: shifted_b = 8
// CHECK: shifted_i = 8
class Int<int value> {
int Value = value;
}