This pass merges inputs of swizzeable instructions into vector sharing common data and/or have enough undef subreg using swizzle abilities. More...

#include "MCTargetDesc/R600MCTargetDesc.h"
#include "R600.h"
#include "R600Defines.h"
#include "R600Subtarget.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineLoopInfo.h"

Macros
#define	DEBUG_TYPE "vec-merger"

Functions
static bool	isImplicitlyDef (MachineRegisterInfo &MRI, Register Reg)
	INITIALIZE_PASS_BEGIN (R600VectorRegMerger, DEBUG_TYPE, "R600 Vector Reg Merger", false, false) INITIALIZE_PASS_END(R600VectorRegMerger
static unsigned	getReassignedChan (const std::vector< std::pair< unsigned, unsigned > > &RemapChan, unsigned Chan)

Variables
	DEBUG_TYPE
R600 Vector Reg	Merger
R600 Vector Reg	false

Detailed Description

This pass merges inputs of swizzeable instructions into vector sharing common data and/or have enough undef subreg using swizzle abilities.

For instance let's consider the following pseudo code : %5 = REG_SEQ %1, sub0, %2, sub1, %3, sub2, undef, sub3 ... %7 = REG_SEQ %1, sub0, %3, sub1, undef, sub2, %4, sub3 (swizzable Inst) %7, SwizzleMask : sub0, sub1, sub2, sub3

is turned into : %5 = REG_SEQ %1, sub0, %2, sub1, %3, sub2, undef, sub3 ... %7 = INSERT_SUBREG %4, sub3 (swizzable Inst) %7, SwizzleMask : sub0, sub2, sub1, sub3

This allow regalloc to reduce register pressure for vector registers and to reduce MOV count.

Definition in file R600OptimizeVectorRegisters.cpp.