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[SCEVValidator] Loop exit values of loops before the SCoP are synthesizable.

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In the following loop:

   int i;
   for (i = 0; i < func(); i+=1)
     ;
SCoP:
   for (int j = 0; j<n; j+=1)
     S(i, j)

The value i is synthesizable in the SCoP that includes only the j-loop.
This is because i is fixed within the SCoP, it is irrelevant whether
it originates from another loop.

This fixes a strange case where a PHI was synthesiable in a SCoP,
but not its incoming value, triggering an assertion.

This should fix MultiSource/Applications/sgefa/sgefa of the
perf-x86_64-penryn-O3-polly-before-vectorizer-unprofitable buildbot.

llvm-svn: 309109
This commit is contained in:
Michael Kruse 2017-07-26 13:05:45 +00:00
parent 092f199188
commit 11ed062258
4 changed files with 147 additions and 6 deletions
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4
polly/lib/Support/SCEVValidator.cpp
View File

@ -506,10 +506,6 @@ public:
if (AllowLoops)
return true;
if (!Scope) {
HasInRegionDeps = true;
return false;
}
auto *L = AddRec->getLoop();
if (R->contains(L) && !L->contains(Scope)) {
HasInRegionDeps = true;

2
polly/test/ScopDetect/index_from_unpredictable_loop.ll
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@ -42,8 +42,6 @@ for.end:
; AFFINE-NEXT: [octets, p_1, p] -> { Stmt_if_then84[] : octets = 2 };
; AFFINE-NEXT: Schedule :=
; AFFINE-NEXT: [octets, p_1, p] -> { Stmt_if_then84[] -> [] };
; AFFINE-NEXT: ReadAccess := [Reduction Type: NONE] [Scalar: 1]
; AFFINE-NEXT: [octets, p_1, p] -> { Stmt_if_then84[] -> MemRef_indvars_iv[] };
; AFFINE-NEXT: MustWriteAccess := [Reduction Type: NONE] [Scalar: 0]
; AFFINE-NEXT: [octets, p_1, p] -> { Stmt_if_then84[] -> MemRef_input[1 + p] };
; AFFINE-NEXT: }

86
polly/test/ScopDetect/index_from_unpredictable_loop2.ll Normal file
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@ -0,0 +1,86 @@
; RUN: opt %loadPolly -polly-scops -analyze < %s | FileCheck %s --check-prefix=AFFINE
; RUN: opt %loadPolly -polly-scops -polly-allow-nonaffine -analyze < %s | FileCheck %s --check-prefix=NONAFFINE
; The loop for.body => for.inc has an unpredictable iteration count could due to
; the undef start value that it is compared to. Therefore the array element
; %arrayidx101 that depends on that exit value cannot be affine.
; Derived from test-suite/MultiSource/Benchmarks/BitBench/uuencode/uuencode.c
define void @encode_line(i8* nocapture readonly %input, i32 %octets, i64 %p, i32 %n) {
entry:
br label %outer.for
outer.for:
%j = phi i32 [0, %entry], [%j.inc, %for.end]
%j.cmp = icmp slt i32 %j, %n
br i1 %j.cmp, label %for.body, label %exit
for.body:
%indvars.iv = phi i64 [ %indvars.iv.next, %for.inc ], [ %p, %outer.for ]
%octets.addr.02 = phi i32 [ undef, %for.inc ], [ %octets, %outer.for ]
br i1 false, label %for.inc, label %if.else
if.else:
%cond = icmp eq i32 %octets.addr.02, 2
br i1 %cond, label %if.then84, label %for.end
if.then84:
%0 = add nsw i64 %indvars.iv, 1
%arrayidx101 = getelementptr inbounds i8, i8* %input, i64 %0
store i8 42, i8* %arrayidx101, align 1
br label %for.end
for.inc:
%cmp = icmp sgt i32 %octets.addr.02, 3
%indvars.iv.next = add nsw i64 %indvars.iv, 3
br i1 %cmp, label %for.body, label %for.end
for.end:
%j.inc = add nuw nsw i32 %j, 1
br label %outer.for
exit:
br label %return
return:
ret void
}
; AFFINE: Region: %if.else---%for.end
; AFFINE: Statements {
; AFFINE-NEXT: Stmt_if_then84
; AFFINE-NEXT: Domain :=
; AFFINE-NEXT: [octets, p_1, p] -> { Stmt_if_then84[] : octets = 2 };
; AFFINE-NEXT: Schedule :=
; AFFINE-NEXT: [octets, p_1, p] -> { Stmt_if_then84[] -> [] };
; AFFINE-NEXT: MustWriteAccess := [Reduction Type: NONE] [Scalar: 0]
; AFFINE-NEXT: [octets, p_1, p] -> { Stmt_if_then84[] -> MemRef_input[1 + p] };
; AFFINE-NEXT: }
; NONAFFINE: Region: %outer.for---%return
; NONAFFINE: Statements {
; NONAFFINE-NEXT: Stmt_for_body
; NONAFFINE-NEXT: Domain :=
; NONAFFINE-NEXT: [n, octets] -> { Stmt_for_body[i0, 0] : 0 <= i0 < n };
; NONAFFINE-NEXT: Schedule :=
; NONAFFINE-NEXT: [n, octets] -> { Stmt_for_body[i0, i1] -> [i0, 0, 0] };
; NONAFFINE-NEXT: MustWriteAccess := [Reduction Type: NONE] [Scalar: 1]
; NONAFFINE-NEXT: [n, octets] -> { Stmt_for_body[i0, i1] -> MemRef_indvars_iv[] };
; NONAFFINE-NEXT: Stmt_if_then84
; NONAFFINE-NEXT: Domain :=
; NONAFFINE-NEXT: [n, octets] -> { Stmt_if_then84[i0] : octets = 2 and 0 <= i0 < n };
; NONAFFINE-NEXT: Schedule :=
; NONAFFINE-NEXT: [n, octets] -> { Stmt_if_then84[i0] -> [i0, 1, 0] };
; NONAFFINE-NEXT: ReadAccess := [Reduction Type: NONE] [Scalar: 1]
; NONAFFINE-NEXT: [n, octets] -> { Stmt_if_then84[i0] -> MemRef_indvars_iv[] };
; NONAFFINE-NEXT: MayWriteAccess := [Reduction Type: NONE] [Scalar: 0]
; NONAFFINE-NEXT: [n, octets] -> { Stmt_if_then84[i0] -> MemRef_input[o0] };
; NONAFFINE-NEXT: }

61
polly/test/ScopInfo/unpredictable_nonscop_loop.ll Normal file
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@ -0,0 +1,61 @@
; RUN: opt %loadPolly -polly-scops -analyze < %s | FileCheck %s -match-full-lines
; Derived from test-suite/MultiSource/Applications/sgefa/blas.c
;
; The exit value of %i.0320 in land.rhs is not computable.
; It is still synthesizable in %if.end13---%for.end170 because
; %i.0320 is fixed within the SCoP and therefore just another parameter.
;
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
define void @snrm2(i32 %n) local_unnamed_addr {
entry:
br label %land.rhs
land.rhs: ; preds = %while.body, %entry
%i.0320 = phi i32 [ 0, %entry ], [ %inc, %while.body ]
br i1 undef, label %while.body, label %if.end13
while.body: ; preds = %land.rhs
%inc = add nuw nsw i32 %i.0320, 1
br label %land.rhs
if.end13: ; preds = %land.rhs
%i.4284 = add nsw i32 %i.0320, 1
%cmp131285 = icmp slt i32 %i.4284, %n
br i1 %cmp131285, label %for.body133.lr.ph, label %for.end170
for.body133.lr.ph: ; preds = %if.end13
br label %for.body133
for.body133: ; preds = %for.body133, %for.body133.lr.ph
%i.4289 = phi i32 [ %i.4284, %for.body133.lr.ph ], [ %i.4, %for.body133 ]
%xmax.2287 = phi float [ undef, %for.body133.lr.ph ], [ undef, %for.body133 ]
%i.4 = add nsw i32 %i.4289, 1
%exitcond = icmp eq i32 %i.4, %n
br i1 %exitcond, label %for.end170, label %for.body133
for.end170: ; preds = %for.body133, %if.end13
ret void
}
; CHECK: Region: %if.end13---%for.end170
; CHECK: Statements {
; CHECK-NEXT: Stmt_for_body133_lr_ph
; CHECK-NEXT: Domain :=
; CHECK-NEXT: [p_0, n] -> { Stmt_for_body133_lr_ph[] : n >= 2 + p_0 };
; CHECK-NEXT: Schedule :=
; CHECK-NEXT: [p_0, n] -> { Stmt_for_body133_lr_ph[] -> [0, 0] };
; CHECK-NEXT: MustWriteAccess := [Reduction Type: NONE] [Scalar: 1]
; CHECK-NEXT: [p_0, n] -> { Stmt_for_body133_lr_ph[] -> MemRef_xmax_2287__phi[] };
; CHECK-NEXT: Stmt_for_body133
; CHECK-NEXT: Domain :=
; CHECK-NEXT: [p_0, n] -> { Stmt_for_body133[i0] : 0 <= i0 <= -2 - p_0 + n };
; CHECK-NEXT: Schedule :=
; CHECK-NEXT: [p_0, n] -> { Stmt_for_body133[i0] -> [1, i0] };
; CHECK-NEXT: MustWriteAccess := [Reduction Type: NONE] [Scalar: 1]
; CHECK-NEXT: [p_0, n] -> { Stmt_for_body133[i0] -> MemRef_xmax_2287__phi[] };
; CHECK-NEXT: ReadAccess := [Reduction Type: NONE] [Scalar: 1]
; CHECK-NEXT: [p_0, n] -> { Stmt_for_body133[i0] -> MemRef_xmax_2287__phi[] };
; CHECK-NEXT: }