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[isl-codegen]: Fix off by one in getNumberOfIterations 

We need to remove one dimension. Any is correct as long as it exists. We have
choosen for whatever reason the dimension #dims - 2. This is incorrect if
there is just one dimension. For CLooG this case did never happen. For isl
however, the case can happen and causes undefined behavior including crashes.
We choose now always the last dimension #dims - 1. We could have choosen
dimension '0' but the last dimension is what we remove conceptionally in the
algorithm, so it seems better to actually program it that way.

While at it remove another piece of undefined behavior.

llvm-svn: 174894
This commit is contained in:
Tobias Grosser 2013-02-11 17:52:36 +00:00
parent 0b8ae895b4
commit c92c8f06ec
2 changed files with 33 additions and 2 deletions
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6
polly/include/polly/CodeGen/CodeGeneration.h
View File

@ -34,13 +34,15 @@ namespace polly {
// and output dimension not related.
// [i0, i1, i2, i3] -> [i0, i1, i2, o0]
isl_space *Space = isl_set_get_space(Domain);
Space = isl_space_drop_outputs(Space, Dim - 2, 1);
Space = isl_space_drop_outputs(Space, Dim - 1, 1);
Space = isl_space_map_from_set(Space);
isl_map *Identity = isl_map_identity(Space);
Identity = isl_map_add_dims(Identity, isl_dim_in, 1);
Identity = isl_map_add_dims(Identity, isl_dim_out, 1);
isl_map *Map = isl_map_from_domain_and_range(isl_set_copy(Domain), Domain);
isl_map *Map = isl_map_from_domain_and_range(isl_set_copy(Domain),
isl_set_copy(Domain));
isl_set_free(Domain);
Map = isl_map_intersect(Map, Identity);
isl_map *LexMax = isl_map_lexmax(isl_map_copy(Map));

29
polly/test/Isl/CodeGen/20130211-getNumberOfIterations.ll Normal file
View File

@ -0,0 +1,29 @@
; RUN: opt %loadPolly -polly-codegen-isl -polly-vectorizer=polly < %s
; RUN: opt %loadPolly -polly-codegen-isl -polly-vectorizer=bb < %s
; This test case checks that the polly vectorizer does not crash when
; calculating the number of iterations.
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-S128"
target triple = "x86_64-unknown-linux-gnu"
@b = external global [2048 x i64], align 16
define void @foo(i64 %n) {
entry:
br label %for.cond
for.cond: ; preds = %for.body, %entry
%indvar = phi i64 [ 0, %entry ], [ %inc, %for.body ]
%cmp = icmp slt i64 %indvar, %n
br i1 %cmp, label %for.body, label %for.end
for.body: ; preds = %for.cond
%arrayidx = getelementptr inbounds [2048 x i64]* @b, i64 0, i64 %indvar
store i64 1, i64* %arrayidx
%inc = add nsw i64 %indvar, 1
br label %for.cond
for.end: ; preds = %for.cond
ret void
}