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[Mem2Reg] Fix nondeterministic corner case
Summary: When mem2reg inserts phi nodes in blocks with unreachable predecessors, it adds undef operands for those incoming edges. When there are multiple such predecessors, the order is currently based on the address of the BasicBlocks. This change fixes that by using the BBNumbers in the sort/search predicates, as is done elsewhere in mem2reg to ensure determinism. Also adds a testcase with a bunch of unreachable preds, which (nodeterministically) fails without the fix. Reviewers: majnemer Reviewed By: majnemer Subscribers: mgrang, llvm-commits Differential Revision: https://reviews.llvm.org/D55077 llvm-svn: 348024
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Original file line number | Diff line number | Diff line change |
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@@ -0,0 +1,53 @@ | ||
;RUN: opt -mem2reg -S < %s | FileCheck %s | ||
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declare i1 @cond() | ||
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define i32 @foo() { | ||
Entry: | ||
%val = alloca i32 | ||
%c1 = call i1 @cond() | ||
br i1 %c1, label %Store1, label %Store2 | ||
Block1: | ||
br label %Join | ||
Block2: | ||
br label %Join | ||
Block3: | ||
br label %Join | ||
Block4: | ||
br label %Join | ||
Block5: | ||
br label %Join | ||
Store1: | ||
store i32 1, i32* %val | ||
br label %Join | ||
Block6: | ||
br label %Join | ||
Block7: | ||
br label %Join | ||
Block8: | ||
br label %Join | ||
Block9: | ||
br label %Join | ||
Block10: | ||
br label %Join | ||
Store2: | ||
store i32 2, i32* %val | ||
br label %Join | ||
Block11: | ||
br label %Join | ||
Block12: | ||
br label %Join | ||
Block13: | ||
br label %Join | ||
Block14: | ||
br label %Join | ||
Block15: | ||
br label %Join | ||
Block16: | ||
br label %Join | ||
Join: | ||
; Phi inserted here should have operands appended deterministically | ||
; CHECK: %val.0 = phi i32 [ 1, %Store1 ], [ 2, %Store2 ], [ undef, %Block1 ], [ undef, %Block2 ], [ undef, %Block3 ], [ undef, %Block4 ], [ undef, %Block5 ], [ undef, %Block6 ], [ undef, %Block7 ], [ undef, %Block8 ], [ undef, %Block9 ], [ undef, %Block10 ], [ undef, %Block11 ], [ undef, %Block12 ], [ undef, %Block13 ], [ undef, %Block14 ], [ undef, %Block15 ], [ undef, %Block16 ] | ||
%result = load i32, i32* %val | ||
ret i32 %result | ||
} |