The primary advantage is that loop optimizations will be applied in a
stable order. This helps debugging and unit test creation. It is also
a better overall implementation without pathologically bad performance
on deep functions.

On large functions (llvm-stress --size=200000 | opt -loops)
Before: 0.1263s
After:  0.0225s

On deep functions (after tweaking llvm-stress, thanks Nadav):
Before: 0.2281s
After:  0.0227s

See r158790 for more comments.

The loop tree is now consistently generated in forward order, but loop
passes are applied in reverse order over the program. If we have a
loop optimization that prefers forward order, that can easily be
achieved by adding a different type of LoopPassManager.

llvm-svn: 159183

Make sure type is not extended or untyped before create a constant of the type. No test case. Found by inspection.

llvm-svn: 159179

Verify that all paths from the entry block to a virtual register read
pass through a def. Enable this check even when MRI->isSSA() is false.

Verify that the live range of a virtual register is live out of all
predecessor blocks, even for PHI-values.

This requires that PHIElimination sometimes inserts IMPLICIT_DEF
instruction in predecessor blocks.

llvm-svn: 159150

Implicitly defined virtual registers can simply have the <undef> bit set
on all uses, and copies can be turned into implicit defs recursively.

Physical registers are a bit trickier. We handle the common case where a
physreg def is used by a nearby instruction in the same basic block. For
more complicated cases, just leave the IMPLICIT_DEF instruction in.

llvm-svn: 159149

When a PHI use is <undef>, don't emit a copy in the predecessor block,
but insert an IMPLICIT_DEF instruction instead. This ensures that
virtual register uses are always jointly dominated by defs, even if some
of them are IMPLICIT_DEF.

llvm-svn: 159121

When the source register to a 2-addr instruction is undefined, there is
no need to attempt any transformations - simply replace the source
register with the destination register.

This also comes up when lowering IMPLICIT_DEF instructions - make sure
the <undef> flag is moved to the new partial register def operand:

  %vreg8<def> = INSERT_SUBREG %vreg9<undef>, %vreg0<kill>, sub_16bit
rewrite undef:
  %vreg8<def> = INSERT_SUBREG %vreg8<undef>, %vreg0<kill>, sub_16bit
convert to:
  %vreg8:sub_16bit<def,read-undef> = COPY %vreg0<kill>

llvm-svn: 159120

llvm-svn: 159112

llvm-svn: 159092

It's simple: Don't treat <undef> operands as uses, and don't assume a
virtual register has a defining instruction unless a real use has been
seen.

llvm-svn: 159061

The ProcessImplicitDefs class can be local to its implementation file.

llvm-svn: 159041

llvm-svn: 159039

llvm-svn: 159030

It is both smaller and faster than DenseMap.

llvm-svn: 159029

Original commit message:
    Allow up to 64 functional units per processor itinerary.

    This patch changes the type used to hold the FU bitset from unsigned to uint64_t.
    This will be needed for some upcoming PowerPC itineraries.

llvm-svn: 159027

Don't try to print out the live range of a physreg.

llvm-svn: 159021

DBG_VALUE instructions could be referring to non-existing virtual
registers.

llvm-svn: 159020

There is no need to check for physreg live ranges. They don't exist any
more.

llvm-svn: 159019

Everyone is using on-demand regunit ranges now.

llvm-svn: 159018

These functions only operate on virtual registers now, and they all have
live ranges.

llvm-svn: 159015

Don't depend on LiveIntervals::hasInterval() to determine if a physreg
is reserved and constant.

llvm-svn: 159013

This should produce the same results as using physreg liveness directly.

llvm-svn: 159009

With regunit liveness permanently enabled, this function would always
return true.

Also remove now obsolete code for checking physreg interference.

llvm-svn: 159006

knows dwarf or not.

llvm-svn: 158993

DwarfUsesRelocationsAcrossSections.

llvm-svn: 158992

a recommit of r127757. Fixes PR9493. Patch by Paul Robinson!

llvm-svn: 158957

boolean flag to an enum: { Fast, Standard, Strict } (default = Standard).

This option controls the creation by optimizations of fused FP ops that store
intermediate results in higher precision than IEEE allows (E.g. FMAs). The
behavior of this option is intended to match the behaviour specified by a
soon-to-be-introduced frontend flag: '-ffuse-fp-ops'.

Fast mode - allows formation of fused FP ops whenever they're profitable.

Standard mode - allow fusion only for 'blessed' FP ops. At present the only
blessed op is the fmuladd intrinsic. In the future more blessed ops may be
added.

Strict mode - allow fusion only if/when it can be proven that the excess
precision won't effect the result.

Note: This option only controls formation of fused ops by the optimizers.  Fused
operations that are explicitly requested (e.g. FMA via the llvm.fma.* intrinsic)
will always be honored, regardless of the value of this option.

Internally TargetOptions::AllowExcessFPPrecision has been replaced by
TargetOptions::AllowFPOpFusion.

llvm-svn: 158956

to be generic across architectures. It has the
following description in the gnu sources:

    Negate the immediate constant

Several Architectures such as x86 have local implementations
of operand modifier 'n' which go beyond the above description
slightly. This won't affect them.

Affected files:

    lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp
        Added 'n' to the switch cases.

    test/CodeGen/Generic/asm-large-immediate.ll
        Generic compiled test (x86 for me)

    test/CodeGen/Mips/asm-large-immediate.ll
        Mips compiled version of the generic one

Contributer: Jack Carter
llvm-svn: 158939

llvm-svn: 158927

to be generic across architectures. It has the
following description in the gnu sources:

    Substitute immediate value without immediate syntax

Several Architectures such as x86 have local implementations
of operand modifier 'c' which go beyond the above description
slightly. To make use of the generic modifiers without overriding
local implementation one can make a call to the base class method
for AsmPrinter::PrintAsmOperand() in the locally derived method's 
"default" case in the switch statement. That way if it is already
defined locally the generic version will never get called.

This change is needed when test/CodeGen/generic/asm-large-immediate.ll
failed on a native Mips board. The test was assuming a generic
implementation was in place.

Affected files:

    lib/Target/Mips/MipsAsmPrinter.cpp:
        Changed the default case to call the base method.
    lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp
        Added 'c' to the switch cases.
    test/CodeGen/Mips/asm-large-immediate.ll
        Mips compiled version of the generic one

Contributer: Jack Carter
llvm-svn: 158925

_umodsi3 libcalls if they have the same arguments. This optimization
was apparently broken if one of the node was replaced in place.
rdar://11714607

llvm-svn: 158900

Old code would only update physreg live intervals.

llvm-svn: 158881

llvm-svn: 158878

I don't think anyone has been using this functionality for a while, and
it is getting in the way of refactoring now.

llvm-svn: 158876

Register allocators depend on it being permanently enabled now.

llvm-svn: 158873

Deterministically enumerate the virtual registers instead.

llvm-svn: 158872

They are living in LiveRegMatrix now.

llvm-svn: 158868

Stop depending on the LiveIntervalUnions in RegAllocBase, they are about
to be removed.

The changes are mostly replacing register alias iterators with regunit
iterators, and querying LiveRegMatrix instrad of RegAllocBase.

InterferenceCache is converted to work with per-regunit
LiveIntervalUnions, and it checks fixed regunit interference separately,
using the fixed live intervals provided by LiveIntervalAnalysis.

The local splitting helper calcGapWeights() is also considering fixed
regunit interference which is kept on the side now.

llvm-svn: 158867

Stop using the LiveIntervalUnions provided by RegAllocBase, they will be
removed soon.

llvm-svn: 158866

Soon we won't need to compute live intervals for physical registers.

llvm-svn: 158865

Filter out physreg candidates with regunit interferrence.
Also compute regmask interference more efficiently.

llvm-svn: 158864