ELF does not imply GNU/Linux. Do not assume GNU conventions just because we

are targeting an ELF platform.  Only fold gs-relative (and fs-relative) loads
if it is actually sensible to do so for the target platform.

This fixes PR13438.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160687 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/X86ISelDAGToDAG.cpp b/lib/Target/X86/X86ISelDAGToDAG.cpp
index 5186482a0dd561b69c30aaf2cbb4aaf0c760cedf..7161854de0a6b9e203361dd2fc856f0900c444db 100644 (file)
--- a/lib/Target/X86/X86ISelDAGToDAG.cpp
+++ b/lib/Target/X86/X86ISelDAGToDAG.cpp
@@ -593,7 +593,7 @@ bool X86DAGToDAGISel::MatchLoadInAddress(LoadSDNode *N, X86ISelAddressMode &AM){
   // For more information see http://people.redhat.com/drepper/tls.pdf
   if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Address))
     if (C->getSExtValue() == 0 && AM.Segment.getNode() == 0 &&
-        Subtarget->isTargetELF())
+        Subtarget->isTargetLinux())
       switch (N->getPointerInfo().getAddrSpace()) {
       case 256:
         AM.Segment = CurDAG->getRegister(X86::GS, MVT::i16);

diff --git a/test/CodeGen/X86/gs-fold.ll b/test/CodeGen/X86/gs-fold.ll
new file mode 100644 (file)
index 0000000..dbec76b
--- /dev/null
+++ b/test/CodeGen/X86/gs-fold.ll
@@ -0,0 +1,20 @@
+; RUN: llc < %s -mtriple=x86_64-unknown-freebsd | FileCheck %s --check-prefix=CHECK-FBSD
+; RUN: llc < %s -mtriple=x86_64-unknown-linux | FileCheck %s --check-prefix=CHECK-LINUX
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+
+%struct.thread = type { i32, i32, i32, i32 }
+
+define i32 @test() nounwind uwtable {
+entry:
+  %0 = load volatile %struct.thread* addrspace(256)* null
+  %c = getelementptr inbounds %struct.thread* %0, i64 0, i32 2
+  %1 = load i32* %c, align 4
+  ret i32 %1
+}
+
+; Check that we are not assuming that gs contains the address of gs if we are not targeting Linux
+; CHECK-FBSD: movq     %gs:0, %rax
+; CHECK-FBSD: movl     8(%rax), %eax
+; Check that we are assuming that gs contains the address of gs if we are targeting Linux
+; CHECK-LINUX: movl    %gs:8, %eax
+