maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

[RegAllocGreedy][Last Chance Recoloring] Emit diagnostics when last chance 

recoloring cut-offs are encountered and register allocation failed.

This is related to PR18747

Patch by MAYUR PANDEY <mayur.p@samsung.com>.

llvm-svn: 205601
This commit is contained in:
Quentin Colombet 2014-04-04 02:05:21 +00:00
parent 9c816f39ad
commit 96bd2a1490
2 changed files with 43 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
llvm/lib/CodeGen/RegAllocGreedy.cpp
View File

@ -37,6 +37,7 @@
#include "llvm/CodeGen/RegAllocRegistry.h"
#include "llvm/CodeGen/RegisterClassInfo.h"
#include "llvm/CodeGen/VirtRegMap.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/PassAnalysisSupport.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
@ -147,6 +148,22 @@ class RAGreedy : public MachineFunctionPass,
RS_Done
};
// Enum CutOffStage to keep a track whether the register allocation failed
// because of the cutoffs encountered in last chance recoloring.
// Note: This is used as bitmask. New value should be next power of 2.
enum CutOffStage {
// No cutoffs encountered
CO_None = 0,
// lcr-max-depth cutoff encountered
CO_Depth = 1,
// lcr-max-interf cutoff encountered
CO_Interf = 2
};
uint8_t CutOffInfo;
#ifndef NDEBUG
static const char *const StageName[];
#endif
@ -1912,6 +1929,7 @@ RAGreedy::mayRecolorAllInterferences(unsigned PhysReg, LiveInterval &VirtReg,
if (Q.collectInterferingVRegs(LastChanceRecoloringMaxInterference) >=
LastChanceRecoloringMaxInterference) {
DEBUG(dbgs() << "Early abort: too many interferences.\n");
CutOffInfo |= CO_Interf;
return false;
}
for (unsigned i = Q.interferingVRegs().size(); i; --i) {
@ -1984,6 +2002,7 @@ unsigned RAGreedy::tryLastChanceRecoloring(LiveInterval &VirtReg,
// Indeed, in that case we may want to cut the search space earlier.
if (Depth >= LastChanceRecoloringMaxDepth) {
DEBUG(dbgs() << "Abort because max depth has been reached.\n");
CutOffInfo |= CO_Depth;
return ~0u;
}
@ -2108,8 +2127,23 @@ bool RAGreedy::tryRecoloringCandidates(PQueue &RecoloringQueue,
unsigned RAGreedy::selectOrSplit(LiveInterval &VirtReg,
SmallVectorImpl<unsigned> &NewVRegs) {
CutOffInfo = CO_None;
LLVMContext &Ctx = MF->getFunction()->getContext();
SmallVirtRegSet FixedRegisters;
return selectOrSplitImpl(VirtReg, NewVRegs, FixedRegisters);
unsigned Reg = selectOrSplitImpl(VirtReg, NewVRegs, FixedRegisters);
if (Reg == ~0U && (CutOffInfo != CO_None)) {
uint8_t CutOffEncountered = CutOffInfo & (CO_Depth | CO_Interf);
if (CutOffEncountered == CO_Depth)
Ctx.emitError(
"register allocation failed: maximum depth for recoloring reached");
else if (CutOffEncountered == CO_Interf)
Ctx.emitError("register allocation failed: maximum interference for "
"recoloring reached");
else if (CutOffEncountered == (CO_Depth | CO_Interf))
Ctx.emitError("register allocation failed: maximum interference and "
"depth for recoloring reached");
}
return Reg;
}
/// Using a CSR for the first time has a cost because it causes push|pop

8
llvm/test/CodeGen/X86/ragreedy-last-chance-recoloring.ll
View File

@ -2,6 +2,12 @@
; Without the last chance recoloring, this test fails with:
; "ran out of registers".
; RUN: not llc -regalloc=greedy -relocation-model=pic -lcr-max-depth=0 < %s 2>&1 | FileCheck %s --check-prefix=CHECK-DEPTH
; Test whether failure due to cutoff for depth is reported
; RUN: not llc -regalloc=greedy -relocation-model=pic -lcr-max-interf=1 < %s 2>&1 | FileCheck %s --check-prefix=CHECK-INTERF
; Test whether failure due to cutoff for interference is reported
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128-n8:16:32-S128"
target triple = "i386-apple-macosx"
@ -12,6 +18,8 @@ target triple = "i386-apple-macosx"
; Function Attrs: nounwind ssp
; CHECK-NOT: ran out of registers during register allocation
; CHECK-INTERF: error: register allocation failed: maximum interference for recoloring reached
; CHECK-DEPTH: error: register allocation failed: maximum depth for recoloring reached
define void @fp_dh_f870bf31fd8ffe068450366e3f05389a(i8* %arg) #0 {
bb:
indirectbr i8* undef, [label %bb85, label %bb206]