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| author | Benjamin Kramer <benny.kra@googlemail.com> | 2013-02-13 13:40:35 +0000 |
|---|---|---|
| committer | Benjamin Kramer <benny.kra@googlemail.com> | 2013-02-13 13:40:35 +0000 |
| commit | f09e02f01a817f4daf95ef8d3f1f2545297d32e7 (patch) | |
| tree | 73711f287e01d7e5e32364dee462c2f1f919aa5c | |
| parent | 0f80f7bfd72c2a3b49bdd2ac6cd611cad0e6938a (diff) | |
| download | llvm-f09e02f01a817f4daf95ef8d3f1f2545297d32e7.tar.gz llvm-f09e02f01a817f4daf95ef8d3f1f2545297d32e7.tar.bz2 llvm-f09e02f01a817f4daf95ef8d3f1f2545297d32e7.tar.xz | |
X86: Disable generation of rep;movsl when %esi is used as a base pointer.
This happens when there is both stack realignment and a dynamic alloca in the
function. If we overwrite %esi (rep;movsl uses fixed registers) we'll lose the
base pointer and the next register spill will write into oblivion.
Fixes PR15249 and unbreaks firefox on i386/freebsd. Mozilla uses dynamic allocas
and freebsd a 4 byte stack alignment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175057 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/Target/X86/X86SelectionDAGInfo.cpp | 8 | ||||
| -rw-r--r-- | test/CodeGen/X86/stack-align-memcpy.ll | 18 |
2 files changed, 26 insertions, 0 deletions
diff --git a/lib/Target/X86/X86SelectionDAGInfo.cpp b/lib/Target/X86/X86SelectionDAGInfo.cpp index 757e8c70a4..f934fdd859 100644 --- a/lib/Target/X86/X86SelectionDAGInfo.cpp +++ b/lib/Target/X86/X86SelectionDAGInfo.cpp @@ -202,6 +202,14 @@ X86SelectionDAGInfo::EmitTargetCodeForMemcpy(SelectionDAG &DAG, DebugLoc dl, SrcPtrInfo.getAddrSpace() >= 256) return SDValue(); + // ESI might be used as a base pointer, in that case we can't simply overwrite + // the register. Fall back to generic code. + const X86RegisterInfo *TRI = + static_cast<const X86RegisterInfo *>(DAG.getTarget().getRegisterInfo()); + if (TRI->hasBasePointer(DAG.getMachineFunction()) && + TRI->getBaseRegister() == X86::ESI) + return SDValue(); + MVT AVT; if (Align & 1) AVT = MVT::i8; diff --git a/test/CodeGen/X86/stack-align-memcpy.ll b/test/CodeGen/X86/stack-align-memcpy.ll new file mode 100644 index 0000000000..74945e5bb1 --- /dev/null +++ b/test/CodeGen/X86/stack-align-memcpy.ll @@ -0,0 +1,18 @@ +; RUN: llc < %s -force-align-stack -mtriple i386-apple-darwin -mcpu=i486 | FileCheck %s + +%struct.foo = type { [88 x i8] } + +; PR15249 +; We can't use rep;movsl here because it clobbers the base pointer in %esi. +define void @test1(%struct.foo* nocapture %x, i32 %y) nounwind { + %dynalloc = alloca i8, i32 %y, align 1 + call void @bar(i8* %dynalloc, %struct.foo* align 4 byval %x) + ret void + +; CHECK: test1: +; CHECK: andl $-16, %esp +; CHECK: movl %esp, %esi +; CHECK-NOT: rep;movsl +} + +declare void @bar(i8* nocapture, %struct.foo* align 4 byval) nounwind |