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Ensure a correct order between memory accesses. 

Ensure that the scalar write access corresponds to the result of a load
instruction appears after the generic read access corresponds to the load
instruction.

llvm-svn: 186419
This commit is contained in:
Hongbin Zheng 2013-07-16 15:20:29 +00:00
parent 5a772dcd84
commit 63cc9467af
7 changed files with 406 additions and 11 deletions
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5
polly/include/polly/TempScopInfo.h
View File

@ -292,7 +292,10 @@ class TempScopInfo : public FunctionPass {
///
/// @param Inst The instruction to be analyzed
/// @param R The SCoP region
void buildScalarDependences(Instruction *Inst, Region *R);
///
/// @return True if the Instruction is used in other BB and a scalar write
/// Access is required.
bool buildScalarDependences(Instruction *Inst, Region *R);
void buildAccessFunctions(Region &RefRegion, BasicBlock &BB);

19
polly/lib/Analysis/TempScopInfo.cpp
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@ -104,11 +104,11 @@ void TempScop::printDetail(raw_ostream &OS, ScalarEvolution *SE, LoopInfo *LI,
}
}
void TempScopInfo::buildScalarDependences(Instruction *Inst, Region *R) {
bool TempScopInfo::buildScalarDependences(Instruction *Inst, Region *R) {
// No need to translate these scalar dependences into polyhedral form, because
// synthesizable scalars can be generated by the code generator.
if (canSynthesize(Inst, LI, SE, R))
return;
return false;
bool AnyCrossStmtUse = false;
BasicBlock *ParentBB = Inst->getParent();
@ -147,12 +147,7 @@ void TempScopInfo::buildScalarDependences(Instruction *Inst, Region *R) {
AccFuncMap[UseParent].push_back(std::make_pair(ScalarAccess, U));
}
// If the Instruction is used outside the statement, we need to build the
// write access.
if (AnyCrossStmtUse) {
IRAccess ScalarAccess(IRAccess::SCALARWRITE, Inst, ZeroOffset, 1, true);
AccFuncMap[ParentBB].push_back(std::make_pair(ScalarAccess, Inst));
}
return AnyCrossStmtUse;
}
IRAccess TempScopInfo::buildIRAccess(Instruction *Inst, Loop *L, Region *R) {
@ -190,8 +185,12 @@ void TempScopInfo::buildAccessFunctions(Region &R, BasicBlock &BB) {
if (isa<LoadInst>(Inst) || isa<StoreInst>(Inst))
Functions.push_back(std::make_pair(buildIRAccess(Inst, L, &R), Inst));
if (!isa<StoreInst>(Inst))
buildScalarDependences(Inst, &R);
if (!isa<StoreInst>(Inst) && buildScalarDependences(Inst, &R)) {
// If the Instruction is used outside the statement, we need to build the
// write access.
IRAccess ScalarAccess(IRAccess::SCALARWRITE, Inst, ZeroOffset, 1, true);
Functions.push_back(std::make_pair(ScalarAccess, Inst));
}
}
if (Functions.empty())

54
polly/test/TempScop/inter_bb_scalar_dep.ll Normal file
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@ -0,0 +1,54 @@
; RUN: opt %loadPolly -basicaa -polly-analyze-ir -disable-polly-intra-scop-scalar-to-array -analyze < %s | FileCheck %s
; RUN: opt %loadPolly -basicaa -polly-analyze-ir -polly-codegen-scev -disable-polly-intra-scop-scalar-to-array -analyze < %s | FileCheck %s
; void f(long A[], int N, int *init_ptr) {
; long i, j;
;
; for (i = 0; i < N; ++i) {
; init = *init_ptr;
; for (i = 0; i < N; ++i) {
; A[i] = init + 2;
; }
; }
; }
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"
target triple = "x86_64-unknown-linux-gnu"
; Function Attrs: nounwind
define void @f(i64* noalias %A, i64 %N, i64* noalias %init_ptr) #0 {
entry:
br label %for.i
for.i: ; preds = %for.i.end, %entry
%indvar.i = phi i64 [ 0, %entry ], [ %indvar.i.next, %for.i.end ]
%indvar.i.next = add nsw i64 %indvar.i, 1
br label %entry.next
entry.next: ; preds = %for.i
%init = load i64* %init_ptr
; CHECK: BB: entry.next
; CHECK: Read init_ptr[0]
; CHECK: Write init[0]
br label %for.j
for.j: ; preds = %for.j, %entry.next
%indvar.j = phi i64 [ 0, %entry.next ], [ %indvar.j.next, %for.j ]
%init_plus_two = add i64 %init, 2
; CHECK: Read init[0]
; CHECK: Write A[{0,+,8}<%for.j>]
%scevgep = getelementptr i64* %A, i64 %indvar.j
store i64 %init_plus_two, i64* %scevgep
%indvar.j.next = add nsw i64 %indvar.j, 1
%exitcond.j = icmp eq i64 %indvar.j.next, %N
br i1 %exitcond.j, label %for.i.end, label %for.j
for.i.end: ; preds = %for.j
%exitcond.i = icmp eq i64 %indvar.i.next, %N
br i1 %exitcond.i, label %return, label %for.i
return: ; preds = %for.i.end
ret void
}
attributes #0 = { nounwind }

58
polly/test/TempScop/intra_and_inter_bb_scalar_dep.ll Normal file
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@ -0,0 +1,58 @@
; RUN: opt %loadPolly -basicaa -polly-analyze-ir -disable-polly-intra-scop-scalar-to-array -analyze < %s | FileCheck %s
; RUN: opt %loadPolly -basicaa -polly-analyze-ir -polly-codegen-scev -disable-polly-intra-scop-scalar-to-array -analyze < %s | FileCheck %s
; void f(long A[], int N, int *init_ptr) {
; long i, j;
;
; for (i = 0; i < N; ++i) {
; init = *init_ptr;
; for (i = 0; i < N; ++i) {
; init2 = *init_ptr;
; A[i] = init + init2;
; }
; }
; }
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"
target triple = "x86_64-unknown-linux-gnu"
; Function Attrs: nounwind
define void @f(i64* noalias %A, i64 %N, i64* noalias %init_ptr) #0 {
entry:
br label %for.i
for.i: ; preds = %for.i.end, %entry
%indvar.i = phi i64 [ 0, %entry ], [ %indvar.i.next, %for.i.end ]
%indvar.i.next = add nsw i64 %indvar.i, 1
br label %entry.next
entry.next: ; preds = %for.i
%init = load i64* %init_ptr
; CHECK: BB: entry.next
; CHECK: Read init_ptr[0]
; CHECK: Write init[0]
br label %for.j
for.j: ; preds = %for.j, %entry.next
%indvar.j = phi i64 [ 0, %entry.next ], [ %indvar.j.next, %for.j ]
%init_2 = load i64* %init_ptr
%init_sum = add i64 %init, %init_2
; CHECK: BB: for.j
; CHECK: Read init[0]
; CHECK: Read init_ptr[0]
; CHECK: Write A[{0,+,8}<%for.j>]
%scevgep = getelementptr i64* %A, i64 %indvar.j
store i64 %init_sum, i64* %scevgep
%indvar.j.next = add nsw i64 %indvar.j, 1
%exitcond.j = icmp eq i64 %indvar.j.next, %N
br i1 %exitcond.j, label %for.i.end, label %for.j
for.i.end: ; preds = %for.j
%exitcond.i = icmp eq i64 %indvar.i.next, %N
br i1 %exitcond.i, label %return, label %for.i
return: ; preds = %for.i.end
ret void
}
attributes #0 = { nounwind }

52
polly/test/TempScop/intra_bb_scalar_dep.ll Normal file
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@ -0,0 +1,52 @@
; RUN: opt %loadPolly -basicaa -polly-analyze-ir -disable-polly-intra-scop-scalar-to-array -analyze < %s | FileCheck %s
; RUN: opt %loadPolly -basicaa -polly-analyze-ir -polly-codegen-scev -disable-polly-intra-scop-scalar-to-array -analyze < %s | FileCheck %s
; void f(long A[], int N, int *init_ptr) {
; long i, j;
;
; for (i = 0; i < N; ++i) {
; for (i = 0; i < N; ++i) {
; init = *init_ptr;
; A[i] = init + 2;
; }
; }
; }
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"
target triple = "x86_64-unknown-linux-gnu"
; Function Attrs: nounwind
define void @f(i64* noalias %A, i64 %N, i64* noalias %init_ptr) #0 {
entry:
br label %for.i
for.i: ; preds = %for.i.end, %entry
%indvar.i = phi i64 [ 0, %entry ], [ %indvar.i.next, %for.i.end ]
%indvar.i.next = add nsw i64 %indvar.i, 1
br label %entry.next
entry.next: ; preds = %for.i
br label %for.j
for.j: ; preds = %for.j, %entry.next
%indvar.j = phi i64 [ 0, %entry.next ], [ %indvar.j.next, %for.j ]
%init = load i64* %init_ptr
%init_plus_two = add i64 %init, 2
%scevgep = getelementptr i64* %A, i64 %indvar.j
store i64 %init_plus_two, i64* %scevgep
; CHECK: BB: for.j
; CHECK: Read init_ptr[0]
; CHECK: Write A[{0,+,8}<%for.j>]
%indvar.j.next = add nsw i64 %indvar.j, 1
%exitcond.j = icmp eq i64 %indvar.j.next, %N
br i1 %exitcond.j, label %for.i.end, label %for.j
for.i.end: ; preds = %for.j
%exitcond.i = icmp eq i64 %indvar.i.next, %N
br i1 %exitcond.i, label %return, label %for.i
return: ; preds = %for.i.end
ret void
}
attributes #0 = { nounwind }

186
polly/test/TempScop/scalar_to_array.ll Normal file
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@ -0,0 +1,186 @@
; RUN: opt %loadPolly -basicaa -polly-analyze-ir -disable-polly-intra-scop-scalar-to-array -analyze < %s | FileCheck %s
; RUN: opt %loadPolly -basicaa -polly-analyze-ir -disable-polly-intra-scop-scalar-to-array -polly-codegen-scev -analyze < %s | FileCheck %s
; ModuleID = 'scalar_to_array.ll'
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-n8:16:32:64"
target triple = "x86_64-unknown-linux-gnu"
@A = common global [1024 x float] zeroinitializer, align 8
; CHECK: empty
; Function Attrs: nounwind
define i32 @empty() #0 {
entry:
fence seq_cst
br label %for.cond
for.cond: ; preds = %for.inc, %entry
%indvar = phi i64 [ %indvar.next, %for.inc ], [ 0, %entry ]
%exitcond = icmp ne i64 %indvar, 1024
br i1 %exitcond, label %for.body, label %return
for.body: ; preds = %for.cond
br label %for.inc
for.inc: ; preds = %for.body
%indvar.next = add i64 %indvar, 1
br label %for.cond
return: ; preds = %for.cond
fence seq_cst
ret i32 0
}
; CHECK: array_access
; Function Attrs: nounwind
define i32 @array_access() #0 {
entry:
fence seq_cst
br label %for.cond
for.cond: ; preds = %for.inc, %entry
%indvar = phi i64 [ %indvar.next, %for.inc ], [ 0, %entry ]
%exitcond = icmp ne i64 %indvar, 1024
br i1 %exitcond, label %for.body, label %return
for.body: ; preds = %for.cond
%arrayidx = getelementptr [1024 x float]* @A, i64 0, i64 %indvar
%float = uitofp i64 %indvar to float
store float %float, float* %arrayidx
br label %for.inc
; CHECK: BB: for.body
; CHECK-NOT: Read
; CHECK: Write A[{0,+,4}<%for.cond>]
for.inc: ; preds = %for.body
%indvar.next = add i64 %indvar, 1
br label %for.cond
return: ; preds = %for.cond
fence seq_cst
ret i32 0
}
; Function Attrs: nounwind
; CHECK: intra_scop_dep
define i32 @intra_scop_dep() #0 {
entry:
fence seq_cst
br label %for.cond
for.cond: ; preds = %for.inc, %entry
%indvar = phi i64 [ %indvar.next, %for.inc ], [ 0, %entry ]
%exitcond = icmp ne i64 %indvar, 1024
br i1 %exitcond, label %for.body.a, label %return
for.body.a: ; preds = %for.cond
%arrayidx = getelementptr [1024 x float]* @A, i64 0, i64 %indvar
%scalar = load float* %arrayidx
br label %for.body.b
; CHECK: BB: for.body.a
; CHECK: Read A[{0,+,4}<%for.cond>]
; CHECK: Write scalar[0]
for.body.b: ; preds = %for.body.a
%arrayidx2 = getelementptr [1024 x float]* @A, i64 0, i64 %indvar
%float = uitofp i64 %indvar to float
%sum = fadd float %scalar, %float
store float %sum, float* %arrayidx2
br label %for.inc
; CHECK: BB: for.body.b
; CHECK: Read scalar[0]
; CHECK: Write A[{0,+,4}<%for.cond>]
for.inc: ; preds = %for.body.b
%indvar.next = add i64 %indvar, 1
br label %for.cond
return: ; preds = %for.cond
fence seq_cst
ret i32 0
}
; It is not possible to have a scop which accesses a scalar element that is
; a global variable. All global variables are pointers containing possibly
; a single element. Hence they do not need to be handled anyways.
; Please note that this is still required when scalar to array rewritting is
; disabled.
; CHECK: use_after_scop
; Function Attrs: nounwind
define i32 @use_after_scop() #0 {
entry:
%scalar.s2a = alloca float
fence seq_cst
br label %for.head
for.head: ; preds = %for.inc, %entry
%indvar = phi i64 [ %indvar.next, %for.inc ], [ 0, %entry ]
br label %for.body
for.body: ; preds = %for.head
%arrayidx = getelementptr [1024 x float]* @A, i64 0, i64 %indvar
%scalar = load float* %arrayidx
store float %scalar, float* %scalar.s2a
; Escaped uses are still required to be rewritten to stack variable.
; CHECK: BB: for.body
; CHECK: Read A[{0,+,4}<%for.head>]
; CHECK: Write scalar.s2a[0]
br label %for.inc
for.inc: ; preds = %for.body
%indvar.next = add i64 %indvar, 1
%exitcond = icmp ne i64 %indvar, 1024
br i1 %exitcond, label %for.head, label %for.after
for.after: ; preds = %for.inc
%scalar.loadoutside = load float* %scalar.s2a
fence seq_cst
%return_value = fptosi float %scalar.loadoutside to i32
br label %return
return: ; preds = %for.after
ret i32 %return_value
}
; We currently do not transform scalar references, that have only read accesses
; in the scop. There are two reasons for this:
;
; o We don't introduce additional memory references which may yield to compile
; time overhead.
; o For integer values, such a translation may block the use of scalar
; evolution on those values.
;
; CHECK: before_scop
; Function Attrs: nounwind
define i32 @before_scop() #0 {
entry:
br label %preheader
preheader: ; preds = %entry
%scalar = fadd float 4.000000e+00, 5.000000e+00
fence seq_cst
br label %for.cond
for.cond: ; preds = %for.inc, %preheader
%indvar = phi i64 [ %indvar.next, %for.inc ], [ 0, %preheader ]
%exitcond = icmp ne i64 %indvar, 1024
br i1 %exitcond, label %for.body, label %return
for.body: ; preds = %for.cond
%arrayidx = getelementptr [1024 x float]* @A, i64 0, i64 %indvar
store float %scalar, float* %arrayidx
br label %for.inc
; CHECK: BB: for.body
; CHECK: Write A[{0,+,4}<%for.cond>]
for.inc: ; preds = %for.body
%indvar.next = add i64 %indvar, 1
br label %for.cond
return: ; preds = %for.cond
fence seq_cst
ret i32 0
}
attributes #0 = { nounwind }

43
polly/test/TempScop/tempscop-printing.ll
View File

@ -1,4 +1,5 @@
; RUN: opt %loadPolly -basicaa -polly-analyze-ir -analyze < %s | FileCheck %s
; RUN: opt %loadPolly -basicaa -polly-analyze-ir -analyze -disable-polly-intra-scop-scalar-to-array < %s | FileCheck %s -check-prefix=SCALARACCESS
; void f(long A[], int N, int *init_ptr) {
; long i, j;
@ -25,9 +26,12 @@ for.i:
entry.next:
; CHECK: BB: entry.next
; SCALARACCESS: BB: entry.next
%init = load i64* %init_ptr
; CHECK: Read init_ptr[0]
; CHECK: Write init.s2a[0]
; SCALARACCESS: Read init_ptr[0]
; SCALARACCESS: Write init[0]
br label %for.j
for.j:
@ -35,6 +39,10 @@ for.j:
; CHECK: BB: for.j
; CHECK: Read init.s2a[0]
; CHECK: Write A[{0,+,8}<%for.j>]
; SCALARACCESS: BB: for.j
; SCALARACCESS: Read init
; SCALARACCESS: Write A[{0,+,8}<%for.j>]
%init_plus_two = add i64 %init, 2
%scevgep = getelementptr i64* %A, i64 %indvar.j
store i64 %init_plus_two, i64* %scevgep
@ -49,3 +57,38 @@ for.i.end:
return:
ret void
}
define void @g(i64* noalias %A, i64 %N, i64* noalias %init_ptr) nounwind {
entry:
br label %for.i
for.i:
%indvar.i = phi i64 [ 0, %entry ], [ %indvar.i.next, %for.i.end ]
%indvar.i.next = add nsw i64 %indvar.i, 1
br label %entry.next
entry.next:
; SCALARACCESS: BB: entry.next
%init = load i64* %init_ptr
; SCALARACCESS: Read init_ptr[0]
; SCALARACCESS: Write init[0]
br label %for.j
for.j:
; SCALARACCESS: BB: for.j
%indvar.j = phi i64 [ 0, %entry.next ], [ %indvar.j.next, %for.j ]
%scevgep = getelementptr i64* %A, i64 %indvar.j
store i64 %init, i64* %scevgep
; SCALARACCESS: Read init
; SCALARACCESS: Write A[{0,+,8}<%for.j>]
%indvar.j.next = add nsw i64 %indvar.j, 1
%exitcond.j = icmp eq i64 %indvar.j.next, %N
br i1 %exitcond.j, label %for.i.end, label %for.j
for.i.end:
%exitcond.i = icmp eq i64 %indvar.i.next, %N
br i1 %exitcond.i, label %return, label %for.i
return:
ret void
}