diff options
author | Oliver Stannard <oliver.stannard@arm.com> | 2015-06-08 16:55:31 +0000 |
---|---|---|
committer | Oliver Stannard <oliver.stannard@arm.com> | 2015-06-08 16:55:31 +0000 |
commit | 7c40b1a7bc87e44b235779353b17db20dc4686f2 (patch) | |
tree | 77fdb35b39c5cfb22608fabe58d1ac4d33aa59a2 /lib/CodeGen/GlobalMerge.cpp | |
parent | 838271c858c35f4aa0622c52b549074318e18f4e (diff) |
Fix assertion failure in global-merge with unused ConstantExpr
The global-merge pass was crashing because it assumes that all ConstantExprs
(reached via the global variables that they use) have at least one user.
I haven't worked out a way to test this, as an unused ConstantExpr cannot be
represented by serialised IR, and global-merge can only be run in llc, which
does not run any passes which can make a ConstantExpr dead.
This (reduced to the point of silliness) C code triggers this bug when compiled
for arm-none-eabi at -O1:
static a = 7;
static volatile b[10] = {&a};
c;
main() {
c = 0;
for (; c < 10;)
printf(b[c]);
}
Differential Revision: http://reviews.llvm.org/D10314
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239308 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/CodeGen/GlobalMerge.cpp')
-rw-r--r-- | lib/CodeGen/GlobalMerge.cpp | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/lib/CodeGen/GlobalMerge.cpp b/lib/CodeGen/GlobalMerge.cpp index df54a9c6916..37b3bf17ed1 100644 --- a/lib/CodeGen/GlobalMerge.cpp +++ b/lib/CodeGen/GlobalMerge.cpp @@ -280,6 +280,8 @@ bool GlobalMerge::doMerge(SmallVectorImpl<GlobalVariable*> &Globals, // users, so look through ConstantExpr... Use *UI, *UE; if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U.getUser())) { + if (CE->use_empty()) + continue; UI = &*CE->use_begin(); UE = nullptr; } else if (isa<Instruction>(U.getUser())) { |