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| author | Mehdi Amini <mehdi.amini@apple.com> | 2016-09-15 20:26:27 +0000 |
|---|---|---|
| committer | Mehdi Amini <mehdi.amini@apple.com> | 2016-09-15 20:26:27 +0000 |
| commit | d880309835d89413b5cbf4e586d9d0ece4556ece (patch) | |
| tree | c6eadbba3efbe70f012e8a56f226490b396491fc /llvm | |
| parent | 3045d703f6a6fb73edafb80f3142d2d7266af9ec (diff) | |
| download | bcm5719-llvm-d880309835d89413b5cbf4e586d9d0ece4556ece.tar.gz bcm5719-llvm-d880309835d89413b5cbf4e586d9d0ece4556ece.zip | |
[GlobalOpt] Dead Eliminate declarations
GlobalOpt is already dead-code-eliminating global definitions. With
this change it also takes care of declarations.
Hopefully this should make it now a strict superset of GlobalDCE.
This is important for LTO/ThinLTO as we don't want the linker to see
"undefined reference" when it processes the input files: it could
prevent proper internalization (or even load an extra file from a
static archive, changing the behavior of the program!).
llvm-svn: 281653
Diffstat (limited to 'llvm')
| -rw-r--r-- | llvm/lib/Transforms/IPO/GlobalOpt.cpp | 4 | ||||
| -rw-r--r-- | llvm/test/Transforms/GlobalOpt/deaddeclaration.ll | 7 |
2 files changed, 9 insertions, 2 deletions
diff --git a/llvm/lib/Transforms/IPO/GlobalOpt.cpp b/llvm/lib/Transforms/IPO/GlobalOpt.cpp index 52c1cc5d279..f1686a0a615 100644 --- a/llvm/lib/Transforms/IPO/GlobalOpt.cpp +++ b/llvm/lib/Transforms/IPO/GlobalOpt.cpp @@ -1653,7 +1653,7 @@ static bool deleteIfDead(GlobalValue &GV, SmallSet<const Comdat *, 8> &NotDiscardableComdats) { GV.removeDeadConstantUsers(); - if (!GV.isDiscardableIfUnused()) + if (!GV.isDiscardableIfUnused() && !GV.isDeclaration()) return false; if (const Comdat *C = GV.getComdat()) @@ -1662,7 +1662,7 @@ static bool deleteIfDead(GlobalValue &GV, bool Dead; if (auto *F = dyn_cast<Function>(&GV)) - Dead = F->isDefTriviallyDead(); + Dead = (F->isDeclaration() && F->use_empty()) || F->isDefTriviallyDead(); else Dead = GV.use_empty(); if (!Dead) diff --git a/llvm/test/Transforms/GlobalOpt/deaddeclaration.ll b/llvm/test/Transforms/GlobalOpt/deaddeclaration.ll new file mode 100644 index 00000000000..942f2e1bf6b --- /dev/null +++ b/llvm/test/Transforms/GlobalOpt/deaddeclaration.ll @@ -0,0 +1,7 @@ +; RUN: opt < %s -globalopt -S | FileCheck %s + +; CHECK-NOT: aa +; CHECK-NOT: bb + +declare void @aa() +@bb = external global i8 |
