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llvm-6502/test/CodeGen/X86/2012-01-16-mfence-nosse-flags.ll
Tim Northover 3e84ad28d4 ISelDAG: spot chain cycles involving MachineNodes
Previously, the DAGISel function WalkChainUsers was spotting that it
had entered already-selected territory by whether a node was a
MachineNode (amongst other things). Since it's fairly common practice
to insert MachineNodes during ISelLowering, this was not the correct
check.

Looking around, it seems that other nodes get their NodeId set to -1
upon selection, so this makes sure the same thing happens to all
MachineNodes and uses that characteristic to determine whether we
should stop looking for a loop during selection.

This should fix PR15840.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191165 91177308-0d34-0410-b5e6-96231b3b80d8
2013-09-22 08:21:56 +00:00

35 lines
888 B
LLVM

; RUN: llc < %s -mtriple=i686-linux -mattr=-sse | FileCheck %s
; PR11768
@ptr = external global i8*
define void @baz() nounwind ssp {
entry:
%0 = load i8** @ptr, align 4
%cmp = icmp eq i8* %0, null
fence seq_cst
br i1 %cmp, label %if.then, label %if.else
; Make sure the fence comes before the comparison, since it
; clobbers EFLAGS.
; CHECK: lock
; CHECK-NEXT: orl {{.*}}, (%esp)
; CHECK-NEXT: testl [[REG:%e[a-z]+]], [[REG]]
if.then: ; preds = %entry
tail call void bitcast (void (...)* @foo to void ()*)() nounwind
br label %if.end
if.else: ; preds = %entry
tail call void bitcast (void (...)* @bar to void ()*)() nounwind
br label %if.end
if.end: ; preds = %if.else, %if.then
ret void
}
declare void @foo(...)
declare void @bar(...)