reserving a physical register ($gp or $28) for that purpose.
This will completely eliminate loads that restore the value of $gp after every
function call, if the register allocator assigns a callee-saved register, or
eliminate unnecessary loads if it assigns a temporary register.
example:
.cpload $25 // set $gp.
...
.cprestore 16 // store $gp to stack slot 16($sp).
...
jalr $25 // function call. clobbers $gp.
lw $gp, 16($sp) // not emitted if callee-saved reg is chosen.
...
lw $2, 4($gp)
...
jalr $25 // function call.
lw $gp, 16($sp) // not emitted if $gp is not live after this instruction.
...
llvm-svn: 151402
This change reduces the number of instructions generated.
For example,
(load (add (sub $n0, $n1), (MipsLo got(s))))
results in the following sequence of instructions:
1. sub $n2, $n0, $n1
2. lw got(s)($n2)
Previously, three instructions were needed.
1. sub $n2, $n0, $n1
2. addiu $n3, $n2, got(s)
3. lw 0($n3)
llvm-svn: 146888
- Modify lowering of global TLS address nodes.
- Modify isel of ThreadPointer.
- Wrap target global TLS address nodes that are operands of loads with WrapperPIC.
- Remove Mips-specific DAG nodes TlsGd, TprelHi and TprelLo, which can be
substituted with other existing nodes.
llvm-svn: 146175
Mips1 does not support double precision loads or stores, therefore two single
precision loads or stores must be used in place of these instructions. This
patch treats double precision loads and stores as if they are legal
instructions until MCInstLowering, instead of generating the single precision
instructions during instruction selection or Prolog/Epilog code insertion.
Without the changes made in this patch, llc produces code that has the same
problem described in r137484 or bails out when
MipsInstrInfo::storeRegToStackSlot or loadRegFromStackSlot is called before
register allocation.
llvm-svn: 137711
integer register to a floating point register. It is not valid to interpret
the value of a floating pointer register as part of a double precision
floating point value after a single precision floating point computational
or move instruction stores its result to the register.
- In the test case, the following code is generated before this patch is
applied:
mtc1 $zero, $f2 ; unformatted copy to $f2
mov.s $f0, $f2 ; $f0 is in single format
sdc1 $f12, 0($sp)
mov.s $f1, $f2 ; $f1 is in single format
c.eq.d $f12, $f0 ; $f0 cannot be interpreted as double
- The following code is generated after this patch is applied:
mtc1 $zero, $f0 ; unformatted copy to $f0
mtc1 $zero, $f1 ; unformatted copy to $f1
c.eq.d $f12, $f0 ; $f0 can be interpreted as double
Bhanu Chetlapalli and Chris Dearman at MIPS technologies reported this bug and
provided the test case.
llvm-svn: 137484
passed the root of the match, even though only a few patterns
actually needed this (one in X86, several in ARM [which should
be refactored anyway], and some in CellSPU that I don't feel
like detangling). Instead of requiring all ComplexPatterns to
take the dead root, have targets opt into getting the root by
putting SDNPWantRoot on the ComplexPattern.
llvm-svn: 114471
