df8e140349
This patch removes the heuristic in
- Polly :: lib/Support/ScopHelper.cpp
The heuristic forces blocks that directly follow a loop header to not to be considered error blocks.
It was introduced in r249611 with the following commit message:
> This replaces the support for user defined error functions by a
> heuristic that tries to determine if a call to a non-pure function
> should be considered "an error". If so the block is assumed not to be
> executed at runtime. While treating all non-pure function calls as
> errors will allow a lot more regions to be analyzed, it will also
> cause us to dismiss a lot again due to an infeasible runtime context.
> This patch tries to limit that effect. A non-pure function call is
> considered an error if it is executed only in conditionally with
> regards to a cheap but simple heuristic.
In the code below `CCK_Abort2()` would be considered as an error block, but not `CCK_Abort1()` due to this heuristic.
```
for (int i = 0; i < n; i+=1) {
if (ErrorCondition1)
CCK_Abort1(); // No __attribute__((noreturn))
if (ErrorCondition2)
CCK_Abort2(); // No __attribute__((noreturn))
}
```
This does not seem useful. Checking error conditions in the beginning of some work is quite common. It causes a switch default-case to be not considered an error block in SPEC's cactuBSSN. The comment justifying the heuristic mentions a "load", which does not seem to be applicable here. It has been proposed to remove the heuristic.
In addition, the patch fixes the following test cases:
- Polly :: ScopDetect/mod_ref_read_pointer.ll
- Polly :: ScopInfo/max-loop-depth.ll
- Polly :: ScopInfo/mod_ref_access_pointee_arguments.ll
- Polly :: ScopInfo/mod_ref_read_pointee_arguments.ll
- Polly :: ScopInfo/mod_ref_read_pointer.ll
- Polly :: ScopInfo/mod_ref_read_pointers.ll
The test cases failed after removing the heuristic.
Differential Revision: https://reviews.llvm.org/D45274
Contributed-by: Lorenzo Chelini <l.chelini@icloud.com>
llvm-svn: 329548
74 lines
2.4 KiB
LLVM
74 lines
2.4 KiB
LLVM
; RUN: opt %loadPolly -polly-scops -analyze < %s | FileCheck %s
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;
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; void bar();
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; void foo(int *A, int *B, long int N, long int M) {
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; for (long int j = 0; j < M; ++j) {
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; bar();
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; for (long int i = 0; i < N; ++i)
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; A[i] += 1;
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; for (long int i = 0; i < N; ++i)
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; A[i] += 1;
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; }
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; }
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;
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; Test to check that the scop only counts loop depth for loops fully contained
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; in the scop.
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; CHECK: Max Loop Depth: 1
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target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
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define void @foo(i32* %A, i32* %B, i64 %N, i64 %M) {
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entry:
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%cmp1 = icmp slt i64 0, %M
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br i1 %cmp1, label %for.body1, label %for.end1
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for.body1: ; preds = %entry, %for.inc1
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%j.0 = phi i64 [ 0, %entry ], [ %j.next, %for.inc1 ]
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call void (...) @bar() #0
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%cmp2 = icmp slt i64 0, %N
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br i1 %cmp2, label %for.body2, label %for.end2
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for.body2: ; preds = %for.body1, %for.inc2
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%i.1 = phi i64 [ 0, %for.body1 ], [ %i.next.1, %for.inc2 ]
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%arrayidx = getelementptr inbounds i32, i32* %A, i64 %i.1
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%tmp = load i32, i32* %arrayidx, align 4
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%add = add nsw i32 %tmp, 1
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store i32 %add, i32* %arrayidx, align 4
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br label %for.inc2
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for.inc2: ; preds = %for.body2
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%i.next.1 = add nuw nsw i64 %i.1, 1
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%cmp3 = icmp slt i64 %i.next.1, %N
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br i1 %cmp3, label %for.body2, label %for.end2
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for.end2: ; preds = %for.inc2, %for.body1
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%cmp4 = icmp slt i64 0, %N
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br i1 %cmp4, label %for.body3, label %for.end3
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for.body3: ; preds = %for.end2
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%i.2 = phi i64 [ 0, %for.end2 ], [ %i.next.2, %for.inc3 ]
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%arrayidx1 = getelementptr inbounds i32, i32* %A, i64 %i.2
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%tmp1 = load i32, i32* %arrayidx1, align 4
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%add1 = add nsw i32 %tmp1, 1
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store i32 %add1, i32* %arrayidx1, align 4
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br label %for.inc3
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for.inc3: ; preds = %for.body3
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%i.next.2 = add nuw nsw i64 %i.2, 1
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%cmp5 = icmp slt i64 %i.next.2, %N
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br i1 %cmp5, label %for.body3, label %for.end3
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for.end3: ; preds = %for.inc3, %for.end2
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br label %for.inc1
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for.inc1: ; preds = %for.end3
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%j.next = add nuw nsw i64 %j.0, 1
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%cmp6 = icmp slt i64 %j.next, %M
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br i1 %cmp6, label %for.body1, label %for.end1
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for.end1: ; preds = %entry, %for.inc1
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ret void
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}
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declare void @bar(...) #0
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