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Allow unsigned comparisons 

With this patch we will optimistically assume that the result of an unsigned
  comparison is the same as the result of the same comparison interpreted as
  signed.

llvm-svn: 267559
This commit is contained in:
Johannes Doerfert 2016-04-26 14:33:12 +00:00
parent 0baa73f317
commit 792374b941
8 changed files with 107 additions and 70 deletions
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27
polly/include/polly/ScopDetectionDiagnostic.h
View File

@ -68,7 +68,6 @@ enum RejectReasonKind {
rrkAffFunc,
rrkUndefCond,
rrkInvalidCond,
rrkUnsignedCond,
rrkUndefOperand,
rrkNonAffBranch,
rrkNoBasePtr,
@ -345,32 +344,6 @@ public:
//@}
};
//===----------------------------------------------------------------------===//
/// @brief Captures an condition on unsigned values
///
/// We do not yet allow conditions on unsigend values
class ReportUnsignedCond : public ReportAffFunc {
//===--------------------------------------------------------------------===//
// The BasicBlock we found the broken condition in.
BasicBlock *BB;
public:
ReportUnsignedCond(const Instruction *Inst, BasicBlock *BB)
: ReportAffFunc(rrkUnsignedCond, Inst), BB(BB) {}
/// @name LLVM-RTTI interface
//@{
static bool classof(const RejectReason *RR);
//@}
/// @name RejectReason interface
//@{
virtual std::string getMessage() const override;
virtual std::string getEndUserMessage() const override;
//@}
};
//===----------------------------------------------------------------------===//
/// @brief Captures an undefined operand.
class ReportUndefOperand : public ReportAffFunc {

12
polly/lib/Analysis/ScopDetection.cpp
View File

@ -149,11 +149,6 @@ static cl::opt<bool>
cl::Hidden, cl::init(false), cl::ZeroOrMore,
cl::cat(PollyCategory));
static cl::opt<bool> AllowUnsigned("polly-allow-unsigned",
cl::desc("Allow unsigned expressions"),
cl::Hidden, cl::init(false), cl::ZeroOrMore,
cl::cat(PollyCategory));
static cl::opt<bool, true>
TrackFailures("polly-detect-track-failures",
cl::desc("Track failure strings in detecting scop regions"),
@ -385,13 +380,6 @@ bool ScopDetection::isValidBranch(BasicBlock &BB, BranchInst *BI,
}
ICmpInst *ICmp = cast<ICmpInst>(Condition);
// Unsigned comparisons are not allowed. They trigger overflow problems
// in the code generation.
//
// TODO: This is not sufficient and just hides bugs. However it does pretty
// well.
if (ICmp->isUnsigned() && !AllowUnsigned)
return invalid<ReportUnsignedCond>(Context, /*Assert=*/true, BI, &BB);
// Are both operands of the ICmp affine?
if (isa<UndefValue>(ICmp->getOperand(0)) ||

16
polly/lib/Analysis/ScopDetectionDiagnostic.cpp
View File

@ -195,22 +195,6 @@ bool ReportInvalidCond::classof(const RejectReason *RR) {
return RR->getKind() == rrkInvalidCond;
}
//===----------------------------------------------------------------------===//
// ReportUnsignedCond.
std::string ReportUnsignedCond::getMessage() const {
return ("Condition in BB '" + BB->getName()).str() +
"' performs a comparision on (not yet supported) unsigned integers.";
}
std::string ReportUnsignedCond::getEndUserMessage() const {
return "Unsupported comparision on unsigned integers encountered";
}
bool ReportUnsignedCond::classof(const RejectReason *RR) {
return RR->getKind() == rrkUnsignedCond;
}
//===----------------------------------------------------------------------===//
// ReportUndefOperand.

12
polly/lib/Analysis/ScopInfo.cpp
View File

@ -1317,6 +1317,18 @@ buildConditionSets(ScopStmt &Stmt, Value *Condition, TerminatorInst *TI,
isl_pw_aff *LHS, *RHS;
LHS = Stmt.getPwAff(SE.getSCEVAtScope(ICond->getOperand(0), L));
RHS = Stmt.getPwAff(SE.getSCEVAtScope(ICond->getOperand(1), L));
if (ICond->isUnsigned()) {
// For unsigned comparisons we assumed the signed bit of neither operand
// to be set. The comparison is equal to a signed comparison under this
// assumption.
auto *BB = Stmt.getEntryBlock();
S.recordAssumption(UNSIGNED, isl_pw_aff_nonneg_set(isl_pw_aff_copy(LHS)),
TI->getDebugLoc(), AS_ASSUMPTION, BB);
S.recordAssumption(UNSIGNED, isl_pw_aff_nonneg_set(isl_pw_aff_copy(RHS)),
TI->getDebugLoc(), AS_ASSUMPTION, BB);
}
ConsequenceCondSet =
buildConditionSet(ICond->getPredicate(), LHS, RHS, Domain);
}

32
polly/test/ScopInfo/simple_loop_unsigned.ll Normal file
View File

@ -0,0 +1,32 @@
; RUN: opt %loadPolly -polly-scops -analyze < %s | FileCheck %s
; void f(int a[], unsigned N) {
; unsigned i;
; do {
; a[i] = i;
; } while (++i <= N);
; }
; CHECK: Assumed Context:
; CHECK-NEXT: [N] -> { : N >= 0 }
;
; CHECK: Domain :=
; CHECK-NEXT: [N] -> { Stmt_bb[i0] : 0 <= i0 < N; Stmt_bb[0] : N <= 0 };
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
define void @f(i64* nocapture %a, i64 %N) nounwind {
entry:
br label %bb
bb: ; preds = %bb, %entry
%i = phi i64 [ 0, %entry ], [ %i.inc, %bb ]
%scevgep = getelementptr inbounds i64, i64* %a, i64 %i
store i64 %i, i64* %scevgep
%i.inc = add nsw i64 %i, 1
%exitcond = icmp uge i64 %i.inc, %N
br i1 %exitcond, label %return, label %bb
return: ; preds = %bb, %entry
ret void
}

25
polly/test/ScopInfo/simple_loop_unsigned_2.ll Normal file
View File

@ -0,0 +1,25 @@
; RUN: opt %loadPolly -polly-scops -analyze < %s | FileCheck %s
; CHECK: Assumed Context:
; CHECK-NEXT: [N] -> { : N > 0 }
;
; CHECK: Domain :=
; CHECK-NEXT: [N] -> { Stmt_bb[i0] : 0 <= i0 < N; Stmt_bb[0] : N <= 0 };
;
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
define void @f(i64* nocapture %a, i64 %N) nounwind {
entry:
br label %bb
bb: ; preds = %bb, %entry
%i = phi i64 [ %N, %entry ], [ %i.dec, %bb ]
%scevgep = getelementptr inbounds i64, i64* %a, i64 %i
store i64 %i, i64* %scevgep
%i.dec = add nsw i64 %i, -1
%exitcond = icmp ugt i64 %i.dec, 0
br i1 %exitcond, label %bb, label %return
return: ; preds = %bb, %entry
ret void
}

26
polly/test/ScopInfo/simple_loop_unsigned_3.ll Normal file
View File

@ -0,0 +1,26 @@
; RUN: opt %loadPolly -polly-scops -analyze < %s | FileCheck %s
; CHECK: Assumed Context:
; CHECK-NEXT: [N] -> { : }
;
; CHECK: Domain :=
; CHECK-NEXT: [N] -> { Stmt_bb[i0] : 0 < i0 <= 1000 - N; Stmt_bb[0] };
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
define void @f(i64* nocapture %a, i64 %N) nounwind {
entry:
br label %bb
bb: ; preds = %bb, %entry
%i = phi i64 [ 1000, %entry ], [ %i.dec, %bb ]
%scevgep = getelementptr inbounds i64, i64* %a, i64 %i
store i64 %i, i64* %scevgep
%i.dec = add nsw i64 %i, -1
%sub = sub nsw i64 %N, %i
%exitcond = icmp ult i64 %sub, 0
br i1 %exitcond, label %bb, label %return
return: ; preds = %bb, %entry
ret void
}

27
polly/test/ScopInfo/unsigned-condition.ll
View File

@ -1,4 +1,4 @@
; RUN: opt %loadPolly -polly-scops -analyze -polly-allow-unsigned < %s | FileCheck %s
; RUN: opt %loadPolly -polly-scops -analyze < %s | FileCheck %s
; void f(int a[], int N, unsigned P) {
; int i;
@ -7,6 +7,17 @@
; a[i] = i;
; }
; The assumed context is the universe because the "signed-unsigned assumption"
; [P, N] -> { : N > 0 and P >= 0 }
; is implied by the execution domain. Thus if something is executed this
; assumption will hold.
; CHECK: Assumed Context:
; CHECK-NEXT: [P, N] -> { : }
;
; CHECK: Domain :=
; CHECK-NEXT: [P, N] -> { Stmt_store[i0] : P >= 42 and 0 <= i0 < N };
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
define void @f(i64* nocapture %a, i64 %N, i64 %P) nounwind {
@ -31,17 +42,3 @@ bb.backedge:
return:
ret void
}
; CHECK: Assumed Context:
; CHECK-NEXT: [P, N] -> { : }
;
; CHECK: Statements {
; CHECK-NEXT: Stmt_store
; CHECK-NEXT: Domain :=
; CHECK-NEXT: [P, N] -> { Stmt_store[i0] : P >= 42 and 0 <= i0 < N };
; CHECK-NEXT: Schedule :=
; CHECK-NEXT: [P, N] -> { Stmt_store[i0] -> [i0] };
; CHECK-NEXT: MustWriteAccess := [Reduction Type: NONE] [Scalar: 0]
; CHECK-NEXT: [P, N] -> { Stmt_store[i0] -> MemRef_a[i0] };
; CHECK-NEXT: }