Early clobbers defining a virtual register were first alocated to a physreg and
then processed as a physreg EC, spilling the virtreg.

This fixes PR7382.

llvm-svn: 105998

register allocation.

Process all of the clobber lists at the end of the function, marking the
registers as used in MachineRegisterInfo.

This is necessary in case the calls clobber callee-saved registers (sic).

llvm-svn: 105473

A partial redef now triggers a reload if required. Also don't add
<imp-def,dead> operands for physical superregisters.

Kill flags are still treated as full register kills, and <imp-use,kill> operands
are added for physical superregisters as before.

llvm-svn: 104167

instruction.

This can happen on ARM:

>> %reg1035:5<def>, %reg1035:6<def> = VLD1q16 %reg1028, 0, pred:14, pred:%reg0
Regs: Q0=%reg1032* R0=%reg1028* R1=%reg1029* R2 R3=%reg1031*
Killing last use: %reg1028
Allocating %reg1035 from QPR
Assigning %reg1035 to Q1
<< %D2<def>, %D3<def> = VLD1q16 %R0<kill>, 0, pred:14, pred:%reg0, %Q1<imp-def>

llvm-svn: 104056

This fixes the miscompilations of MultiSource/Applications/JM/l{en,de}cod.
Clang now successfully self hosts in a debug build with the fast register allocator.

llvm-svn: 103975

llvm-svn: 103961

While that approach works wonders for register pressure, it tends to break
everything.

This should unbreak the arm-linux builder and fix a number of miscompilations.

llvm-svn: 103946

llvm-svn: 103940

out aliases when allocating. Clean up allocVirtReg().

Use calcSpillCost() to allow more aggressive hinting. Now the hint is always
taken unless blocked by a reserved register. This leads to more coalescing,
lower register pressure, and less spilling.

llvm-svn: 103939

This makes allocation independent on the ordering of use-def chains.

llvm-svn: 103935

llvm-svn: 103934

This is safe to do because the physreg has been marked UsedInInstr and the kill flag will be set on the last operand using the virtreg if there are more then one.

llvm-svn: 103933

llvm-svn: 103931

through the very long list of call-clobbered registers. We just assume all
registers are clobbered.

llvm-svn: 103930

llvm-svn: 103929

Debug code doesn't use callee saved registers anyway, and the code is simpler this way. Now spillVirtReg always kills, and the isKill parameter is not needed.

llvm-svn: 103927

llvm-svn: 103926

llvm-svn: 103925

a condition's grouping. Every other use of Allocatable.test(Hint) groups it the
same way as it is indented, so move the parentheses to agree with that
grouping.

llvm-svn: 103869

When working top-down in a basic block, substituting physregs for virtregs, the use-def chains are kept up to date. That means we can recognize a virtreg kill by the use-def chain becoming empty.

This makes the fast allocator independent of incoming kill flags.

llvm-svn: 103866

llvm-svn: 103831

llvm-svn: 103828

llvm-svn: 103823

llvm-svn: 103821

llvm-svn: 103820

- Kill is implicit when use and def registers are identical.
- Only virtual registers can differ.

Add a -verify-fast-regalloc to run the verifier before the fast allocator.

llvm-svn: 103797

This adds extra security against using clobbered physregs, and it adds kill
markers to physreg uses.

llvm-svn: 103784

llvm-svn: 103764

llvm-svn: 103748

This loop is quadratic in the capacity for a DenseMap:

  while(!map.empty())
    map.erase(map.begin());

Instead we now do a normal begin() - end() iteration followed by map.clear().
That also has the nice sideeffect of shrinking the map capacity on demand.

llvm-svn: 103747

llvm-svn: 103739

This causes way more identity copies to be generated, ripe for coalescing.

llvm-svn: 103686

llvm-svn: 103685

The X86 floating point stack pass and others depend on good kill flags.

llvm-svn: 103635

llvm-svn: 103530

llvm-svn: 103528

llvm-svn: 103522

This allows us to add accurate kill markers, something the scavenger likes.
Add some more tests from ARM that needed this.

llvm-svn: 103521

closure after allocating all blocks.

Add a few more test cases for -regalloc=fast.

llvm-svn: 103500

Sorry for the big change. The path leading up to this patch had some TableGen
changes that I didn't want to commit before I knew they were useful. They
weren't, and this version does not need them.

The fast register allocator now does no liveness calculations. Instead it relies
on kill flags provided by isel. (Currently those kill flags are also ignored due
to isel bugs). The allocation algorithm is supposed to work with any subset of
valid kill flags. More kill flags simply means fewer spills inserted.

Registers are allocated from a working set that contains no aliases. That means
most allocations can be done directly without expensive alias checks. When the
working set runs out of registers we do the full alias check to find new free
registers.

llvm-svn: 103488