1 files changed, 86 insertions, 0 deletions
diff --git a/llvm/test/CodeGen/X86/cmpxchg-clobber-flags.ll b/llvm/test/CodeGen/X86/cmpxchg-clobber-flags.ll
new file mode 100644
index 00000000000..3cb8b97de45
--- /dev/null
+++ b/llvm/test/CodeGen/X86/cmpxchg-clobber-flags.ll
@@ -0,0 +1,86 @@
+; RUN: llc -mtriple=x86_64-linux-gnu %s -o - | FileCheck %s
+; RUN: llc -mtriple=x86_64-linux-gnu -pre-RA-sched=fast %s -o - | FileCheck %s
+
+declare i32 @bar()
+
+define i64 @test_intervening_call(i64* %foo, i64 %bar, i64 %baz) {
+; CHECK-LABEL: test_intervening_call:
+; CHECK: cmpxchg
+; CHECK: pushfq
+; CHECK: popq [[FLAGS:%.*]]
+
+; CHECK: callq bar
+
+; CHECK: pushq [[FLAGS]]
+; CHECK: popfq
+; CHECK: jne
+  %cx = cmpxchg i64* %foo, i64 %bar, i64 %baz seq_cst seq_cst
+  %p = extractvalue { i64, i1 } %cx, 1
+  call i32 @bar()
+  br i1 %p, label %t, label %f
+
+t:
+  ret i64 42
+
+f:
+  ret i64 0
+}
+
+; Interesting in producing a clobber without any function calls.
+define i32 @test_control_flow(i32* %p, i32 %i, i32 %j) {
+; CHECK-LABEL: test_control_flow:
+
+; CHECK: cmpxchg
+; CHECK-NEXT: jne
+entry:
+  %cmp = icmp sgt i32 %i, %j
+  br i1 %cmp, label %loop_start, label %cond.end
+
+loop_start:
+  br label %while.condthread-pre-split.i
+
+while.condthread-pre-split.i:
+  %.pr.i = load i32* %p, align 4
+  br label %while.cond.i
+
+while.cond.i:
+  %0 = phi i32 [ %.pr.i, %while.condthread-pre-split.i ], [ 0, %while.cond.i ]
+  %tobool.i = icmp eq i32 %0, 0
+  br i1 %tobool.i, label %while.cond.i, label %while.body.i
+
+while.body.i:
+  %.lcssa = phi i32 [ %0, %while.cond.i ]
+  %1 = cmpxchg i32* %p, i32 %.lcssa, i32 %.lcssa seq_cst seq_cst
+  %2 = extractvalue { i32, i1 } %1, 1
+  br i1 %2, label %cond.end.loopexit, label %while.condthread-pre-split.i
+
+cond.end.loopexit:
+  br label %cond.end
+
+cond.end:
+  %cond = phi i32 [ %i, %entry ], [ 0, %cond.end.loopexit ]
+  ret i32 %cond
+}
+
+; This one is an interesting case because CMOV doesn't have a chain
+; operand. Naive attempts to limit cmpxchg EFLAGS use are likely to fail here.
+define i32 @test_feed_cmov(i32* %addr, i32 %desired, i32 %new) {
+; CHECK-LABEL: test_feed_cmov:
+
+; CHECK: cmpxchg
+; CHECK: pushfq
+; CHECK: popq [[FLAGS:%.*]]
+
+; CHECK: callq bar
+
+; CHECK: pushq [[FLAGS]]
+; CHECK: popfq
+
+  %res = cmpxchg i32* %addr, i32 %desired, i32 %new seq_cst seq_cst
+  %success = extractvalue { i32, i1 } %res, 1
+
+  %rhs = call i32 @bar()
+
+  %ret = select i1 %success, i32 %new, i32 %rhs
+  ret i32 %ret
+}