[llvm] r309355 - [JumpThreading] Stop falsely preserving LazyValueInfo.

[Davide Italiano via llvm-commits]

Author: davide
Date: Thu Jul 27 20:10:43 2017
New Revision: 309355

URL: http://llvm.org/viewvc/llvm-project?rev=309355&view=rev
Log:
[JumpThreading] Stop falsely preserving LazyValueInfo.

JumpThreading claims to preserve LVI, but it doesn't preserve
the analyses which LVI holds a reference to (e.g. the Dominator).
In the current pass manager infrastructure, after JT runs, the
PM frees these analyses (including DominatorTree) but preserves
LVI.

CorrelatedValuePropagation runs immediately after and queries
a corrupted domtree, causing weird miscompiles.

This commit disables the preservation of LVI for the time being.
Eventually, we should either move LVI to a proper dependency
tracking mechanism (i.e. an analyses shouldn't hold references
to other analyses and compute them on demand if needed), or
we should teach all the passes preserving LVI to preserve the
analyses LVI depends on.

The new pass manager has a mechanism to invalidate LVI in case
one of the analyses it depends on becomes invalid, so this problem
shouldn't exist (at least not in this immediate form), but handling
of analyses holding references is still a very delicate subject.

Fixes PR33917 (and rustc).

Added:
    llvm/trunk/test/Transforms/JumpThreading/pr33917.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp?rev=309355&r1=309354&r2=309355&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp Thu Jul 27 20:10:43 2017
@@ -102,7 +102,6 @@ namespace {
         AU.addRequired<DominatorTreeWrapperPass>();
       AU.addRequired<AAResultsWrapperPass>();
       AU.addRequired<LazyValueInfoWrapperPass>();
-      AU.addPreserved<LazyValueInfoWrapperPass>();
       AU.addPreserved<GlobalsAAWrapperPass>();
       AU.addRequired<TargetLibraryInfoWrapperPass>();
     }

Added: llvm/trunk/test/Transforms/JumpThreading/pr33917.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/JumpThreading/pr33917.ll?rev=309355&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/JumpThreading/pr33917.ll (added)
+++ llvm/trunk/test/Transforms/JumpThreading/pr33917.ll Thu Jul 27 20:10:43 2017
@@ -0,0 +1,57 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -jump-threading -correlated-propagation %s -S | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+declare i8* @foo()
+
+declare i32 @rust_eh_personality() unnamed_addr
+
+; Function Attrs: nounwind
+declare void @llvm.assume(i1) #0
+
+define void @patatino() personality i32 ()* @rust_eh_personality {
+; CHECK-LABEL: @patatino(
+; CHECK-NEXT:  bb9:
+; CHECK-NEXT:    [[T9:%.*]] = invoke i8* @foo()
+; CHECK-NEXT:    to label [[GOOD:%.*]] unwind label [[BAD:%.*]]
+; CHECK:       bad:
+; CHECK-NEXT:    [[T10:%.*]] = landingpad { i8*, i32 }
+; CHECK-NEXT:    cleanup
+; CHECK-NEXT:    resume { i8*, i32 } [[T10]]
+; CHECK:       good:
+; CHECK-NEXT:    [[T11:%.*]] = icmp ne i8* [[T9]], null
+; CHECK-NEXT:    [[T12:%.*]] = zext i1 [[T11]] to i64
+; CHECK-NEXT:    [[COND:%.*]] = icmp eq i64 [[T12]], 1
+; CHECK-NEXT:    br i1 [[COND]], label [[IF_TRUE:%.*]], label [[DONE:%.*]]
+; CHECK:       if_true:
+; CHECK-NEXT:    call void @llvm.assume(i1 [[T11]])
+; CHECK-NEXT:    br label [[DONE]]
+; CHECK:       done:
+; CHECK-NEXT:    ret void
+;
+bb9:
+  %t9 = invoke i8* @foo()
+  to label %good unwind label %bad
+
+bad:
+  %t10 = landingpad { i8*, i32 }
+  cleanup
+  resume { i8*, i32 } %t10
+
+good:
+  %t11 = icmp ne i8* %t9, null
+  %t12 = zext i1 %t11 to i64
+  %cond = icmp eq i64 %t12, 1
+  br i1 %cond, label %if_true, label %done
+
+if_true:
+  call void @llvm.assume(i1 %t11)
+  br label %done
+
+done:
+  ret void
+}
+
+attributes #0 = { nounwind }