SelectionDAGBuilder: Fix SPDescriptor not resetting GuardReg

This was causing problems when some functions use a GuardReg and some
don't as can happen when mixing SelectionDAG and FastISel generated
functions.

llvm-svn: 246075

2 files changed, 45 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
index 40f476c355e..854e6d0f170 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -516,6 +516,7 @@ private:
     void resetPerFunctionState() {
       FailureMBB = nullptr;
       Guard = nullptr;
+      GuardReg = 0;
     }
 
     MachineBasicBlock *getParentMBB() { return ParentMBB; }
diff --git a/llvm/test/CodeGen/X86/fast-isel-stackcheck.ll b/llvm/test/CodeGen/X86/fast-isel-stackcheck.ll
new file mode 100644
index 00000000000..3b7318fa77d
--- /dev/null
+++ b/llvm/test/CodeGen/X86/fast-isel-stackcheck.ll
@@ -0,0 +1,44 @@
+; RUN: llc -o - %s | FileCheck %s
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx"
+
+; selectiondag stack protector uses a GuardReg which the fast-isel stack
+; protection code did not but the state was not reset properly.
+; The optnone attribute on @bar forces fast-isel.
+
+; CHECK-LABEL: foo:
+; CHECK: movq ___stack_chk_guard@GOTPCREL(%rip), %rax
+; CHECK-NOT: movq ___stack_chk_guard@GOTPCREL(%rip), %rax
+define void @foo() #0 {
+entry:
+  %_tags = alloca [3 x i32], align 4
+  ret void
+}
+
+; CHECK-LABEL: bar:
+; CHECK: movq ___stack_chk_guard@GOTPCREL(%rip), %rax
+; CHECK: movq ___stack_chk_guard@GOTPCREL(%rip), %rax
+define void @bar() #1 {
+entry:
+  %vt = alloca [2 x double], align 16
+  br i1 undef, label %cleanup.4091, label %for.cond.3850
+
+unreachable:
+  unreachable
+
+for.cond.3850:
+  br i1 undef, label %land.rhs.3853, label %land.end.3857
+
+land.rhs.3853:
+  br label %land.end.3857
+
+land.end.3857:
+  %0 = phi i1 [ false, %for.cond.3850 ], [ false, %land.rhs.3853 ]
+  br i1 %0, label %unreachable, label %unreachable
+
+cleanup.4091:
+  ret void
+}
+
+attributes #0 = { ssp }
+attributes #1 = { noinline optnone ssp }