* Model FPSW (the FPU status word) as a register.
* Add ISel patterns for the FUCOM*, FNSTSW and SAHF instructions.
* During Legalize/Lowering, build a node sequence to transfer the comparison
result from FPSW into EFLAGS. If you're wondering about the right-shift: That's
an implicit sub-register extraction (%ax -> %ah) which is handled later on by
the instruction selector.
Fixes PR6679. Patch by Christoph Erhardt!
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Drop the FpMov instructions, use plain COPY instead.
Drop the FpSET/GET instruction for accessing fixed stack positions.
Instead use normal COPY to/from ST registers around inline assembly, and
provide a single new FpPOP_RETVAL instruction that can access the return
value(s) from a call. This is still necessary since you cannot tell from
the CALL instruction alone if it returns anything on the FP stack. Teach
fast isel to use this.
This provides a much more robust way of handling fixed stack registers -
we can tolerate arbitrary FP stack instructions inserted around calls
and inline assembly. Live range splitting could sometimes break x87 code
by inserting spill code in unfortunate places.
As a bonus we handle floating point inline assembly correctly now.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@134018 91177308-0d34-0410-b5e6-96231b3b80d8
These are just FXSAVE and FXRSTOR with REX.W prefixes. These versions use
64-bit pointer values instead of 32-bit pointer values in the memory map they
dump and restore.
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exposed:
GAS doesn't accept "fcomip %st(1)", it requires "fcomip %st(1), %st(0)"
even though st(0) is implicit in all other fp stack instructions.
Fortunately, there is an alias for fcomip named "fcompi" and gas does
accept the default argument for the alias (boggle!).
As such, switch the canonical form of this instruction to "pi" instead
of "ip". This makes the code generator and disassembler generate pi,
avoiding the gas bug.
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It doesn't look like anything is wrong with the checkin,
but the new test cases expose a mem bug in AsmParser.
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sense, when the instruction takes the 16-bit ax register or m16 memory
location. These changes to llvm-mc matches what the darwin assembler allows
for these instructions. Also added the missing flex (without the wait prefix)
and ud2a as an alias to ud2 (still to add ud2b).
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pass that inserted it.
It is no longer necessary to limit the live ranges of FP registers to a single
basic block.
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instructions as the Mac OS X darwin assembler. Some of which like 'fcoml'
assembled to different opcodes. While some of the suffixes were just different.
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to input patterns, we can fix X86ISD::CMP and X86ISD::BT as taking
two inputs (which have to be the same type) and *returning an i32*.
This is how the SDNodes get made in the graph, but we weren't able
to model it this way due to deficiencies in the pattern language.
Now we can change things like this:
def UCOM_FpIr80: FpI_<(outs), (ins RFP80:$lhs, RFP80:$rhs), CompareFP,
- [(X86cmp RFP80:$lhs, RFP80:$rhs),
- (implicit EFLAGS)]>; // CC = ST(0) cmp ST(i)
+ [(set EFLAGS, (X86cmp RFP80:$lhs, RFP80:$rhs))]>;
and fix terrible crimes like this:
-def : Pat<(parallel (X86cmp GR8:$src1, 0), (implicit EFLAGS)),
+def : Pat<(X86cmp GR8:$src1, 0),
(TEST8rr GR8:$src1, GR8:$src1)>;
This relies on matching the result of TEST8rr (which is EFLAGS, which is
an implicit def) to the result of X86cmp, an i32.
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bunch of associated comments, because it doesn't have anything to do
with DAGs or scheduling. This is another step in decoupling MachineInstr
emitting from scheduling.
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All of these do not have patterns (they're for the
disassembler).
Many of the floating-point instructions will probably
be rolled into definitions that have patterns, and may
eventually be superseded by mdefs. So I put them
together and left a comment.
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llvm's output .s files will go through gcc -std=c99
without triggering preprocesser errors. Approach
suggested by Daveed Vandevoorde.
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x86-64 return conventions correct, but was never enabled.
We can now do the "right thing" with multiple return values.
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isel'ing value preserving FP roundings from one fp stack reg to another
into a noop, instead of stack traffic.
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