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[IRCE] Optimize "uses" not branches; NFCI 

This changes IRCE to optimize uses, and not branches.  This change is
NFCI since the uses we do inspect are in practice only ever going to be
the condition use in conditional branches; but this flexibility will
later allow us to analyze more complex expressions than just a direct
branch on a range check.

llvm-svn: 270500
This commit is contained in:
Sanjoy Das 2016-05-23 22:16:45 +00:00
parent 90770c7c76
commit aa83c47bab
3 changed files with 12 additions and 11 deletions
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19
llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp
View File

@ -118,7 +118,7 @@ class InductiveRangeCheck {
const SCEV *Offset;
const SCEV *Scale;
Value *Length;
BranchInst *Branch;
Use *CheckUse;
RangeCheckKind Kind;
static RangeCheckKind parseRangeCheckICmp(Loop *L, ICmpInst *ICI,
@ -129,8 +129,9 @@ class InductiveRangeCheck {
parseRangeCheck(Loop *L, ScalarEvolution &SE, Value *Condition,
const SCEV *&Index, Value *&UpperLimit);
InductiveRangeCheck() :
Offset(nullptr), Scale(nullptr), Length(nullptr), Branch(nullptr) { }
InductiveRangeCheck()
: Offset(nullptr), Scale(nullptr), Length(nullptr),
CheckUse(nullptr) {}
public:
const SCEV *getOffset() const { return Offset; }
@ -149,9 +150,9 @@ public:
Length->print(OS);
else
OS << "(null)";
OS << "\n Branch: ";
getBranch()->print(OS);
OS << "\n";
OS << "\n CheckUse: ";
getCheckUse()->getUser()->print(OS);
OS << " Operand: " << getCheckUse()->getOperandNo() << "\n";
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
@ -160,7 +161,7 @@ public:
}
#endif
BranchInst *getBranch() const { return Branch; }
Use *getCheckUse() const { return CheckUse; }
/// Represents an signed integer range [Range.getBegin(), Range.getEnd()). If
/// R.getEnd() sle R.getBegin(), then R denotes the empty range.
@ -407,7 +408,7 @@ InductiveRangeCheck::create(BranchInst *BI, Loop *L, ScalarEvolution &SE,
IRC.Length = Length;
IRC.Offset = IndexAddRec->getStart();
IRC.Scale = IndexAddRec->getStepRecurrence(SE);
IRC.Branch = BI;
IRC.CheckUse = &BI->getOperandUse(0);
IRC.Kind = RCKind;
return IRC;
}
@ -1474,7 +1475,7 @@ bool InductiveRangeCheckElimination::runOnLoop(Loop *L, LPPassManager &LPM) {
ConstantInt *FoldedRangeCheck = IRC.getPassingDirection()
? ConstantInt::getTrue(Context)
: ConstantInt::getFalse(Context);
IRC.getBranch()->setCondition(FoldedRangeCheck);
IRC.getCheckUse()->set(FoldedRangeCheck);
}
}

2
llvm/test/Transforms/IRCE/only-lower-check.ll
View File

@ -4,7 +4,7 @@
; CHECK-NEXT: InductiveRangeCheck:
; CHECK-NEXT: Kind: RANGE_CHECK_LOWER
; CHECK-NEXT: Offset: (-1 + %n) Scale: -1 Length: (null)
; CHECK-NEXT: Branch: br i1 %abc, label %in.bounds, label %out.of.bounds
; CHECK-NEXT: CheckUse: br i1 %abc, label %in.bounds, label %out.of.bounds, !prof !1 Operand: 0
; CHECK-NEXT: irce: in function only_lower_check: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
define void @only_lower_check(i32 *%arr, i32 *%a_len_ptr, i32 %n) {

2
llvm/test/Transforms/IRCE/only-upper-check.ll
View File

@ -4,7 +4,7 @@
; CHECK-NEXT:InductiveRangeCheck:
; CHECK-NEXT: Kind: RANGE_CHECK_UPPER
; CHECK-NEXT: Offset: %offset Scale: 1 Length: %len = load i32, i32* %a_len_ptr, !range !0
; CHECK-NEXT: Branch: br i1 %abc, label %in.bounds, label %out.of.bounds, !prof !1
; CHECK-NEXT: CheckUse: br i1 %abc, label %in.bounds, label %out.of.bounds, !prof !1 Operand: 0
; CHECK-NEXT: irce: in function incrementing: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
define void @incrementing(i32 *%arr, i32 *%a_len_ptr, i32 %n, i32 %offset) {