[polly] r245176 - Add a crashing test case for the scalar code generation

[Johannes Doerfert via llvm-commits]

Author: jdoerfert
Date: Sun Aug 16 06:12:22 2015
New Revision: 245176

URL: http://llvm.org/viewvc/llvm-project?rev=245176&view=rev
Log:
Add a crashing test case for the scalar code generation

  This test case crashes the scalar code generation as we are not
  consistent with the usage of the assumed context. To be precise, we
  use the assumed context for the dependence analysis but not to
  restrict the domains of the statements.

  A step by step explanation of the problem is given in the test case.


Added:
    polly/trunk/test/Isl/CodeGen/assumed_context_empty_domain_restriction.ll

Added: polly/trunk/test/Isl/CodeGen/assumed_context_empty_domain_restriction.ll
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/test/Isl/CodeGen/assumed_context_empty_domain_restriction.ll?rev=245176&view=auto
==============================================================================
--- polly/trunk/test/Isl/CodeGen/assumed_context_empty_domain_restriction.ll (added)
+++ polly/trunk/test/Isl/CodeGen/assumed_context_empty_domain_restriction.ll Sun Aug 16 06:12:22 2015
@@ -0,0 +1,66 @@
+; RUN: opt %loadPolly -S -polly-opt-isl -polly-codegen < %s
+;
+; TODO: This test will crash the scalar code generation. The problem step by step:
+;         1) The assumed context is empty because of the out-of-bounds array access.
+;         2) The dependence analysis will use the assumed context and determine
+;            that there are not iterations executed, hence no dependences.
+;         3) The scheduler will transform the program somehow according to
+;            the orginal domains and empty dependences but not the assumed context.
+;            The new ast is shown below.
+;         4) The code generation will look for the new value of %0 when the
+;            for_body_328_lr_ph statement is copied, however it has not yet seen %0
+;            as the for_end_310 statement has been moved after for_body_328_lr_ph.
+;         5) Crash as no new value of %0 can be found.
+;
+; AST:
+;
+;   if (0)
+;       {
+;         for (int c0 = 0; c0 <= 32; c0 += 1)
+;           Stmt_for_body_328(c0);
+;         Stmt_for_body_328_lr_ph();
+;         Stmt_for_end_310();
+;       }
+;   else
+;       {  /* original code */ }
+;
+; CHECK: polly.start
+;
+ at endposition = external global i32, align 4
+ at Bit = external global [0 x i32], align 4
+ at Init = external global [0 x i32], align 4
+
+define void @maskgen() {
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+  br i1 undef, label %for.end.310, label %for.body
+
+for.end.310:                                      ; preds = %for.body
+  store i32 undef, i32* @endposition, align 4
+  %sub325 = sub i32 33, 0
+  %0 = load i32, i32* getelementptr inbounds ([0 x i32], [0 x i32]* @Init, i64 0, i64 0), align 4
+  br i1 false, label %for.cond.347.preheader, label %for.body.328.lr.ph
+
+for.body.328.lr.ph:                               ; preds = %for.end.310
+  %1 = sub i32 34, 0
+  br label %for.body.328
+
+for.body.328:                                     ; preds = %for.body.328, %for.body.328.lr.ph
+  %indvars.iv546 = phi i64 [ %indvars.iv.next547, %for.body.328 ], [ 1, %for.body.328.lr.ph ]
+  %2 = phi i32 [ %or331, %for.body.328 ], [ %0, %for.body.328.lr.ph ]
+  %arrayidx330 = getelementptr inbounds [0 x i32], [0 x i32]* @Bit, i64 0, i64 %indvars.iv546
+  %3 = load i32, i32* %arrayidx330, align 4
+  %or331 = or i32 %3, %2
+  %indvars.iv.next547 = add nuw nsw i64 %indvars.iv546, 1
+  %lftr.wideiv = trunc i64 %indvars.iv.next547 to i32
+  %exitcond14 = icmp eq i32 %lftr.wideiv, %1
+  br i1 %exitcond14, label %for.cond.347.preheader, label %for.body.328
+
+for.cond.347.preheader:                           ; preds = %for.cond.347.preheader, %for.body.328, %for.end.310
+  br i1 undef, label %if.end.471, label %for.cond.347.preheader
+
+if.end.471:                                       ; preds = %for.cond.347.preheader
+  ret void
+}