1 files changed, 73 insertions, 0 deletions
diff --git a/test/CodeGen/X86/pr20020.ll b/test/CodeGen/X86/pr20020.ll
new file mode 100644
index 0000000..83dae36
--- /dev/null
+++ b/test/CodeGen/X86/pr20020.ll
@@ -0,0 +1,73 @@
+; RUN: llc < %s -mtriple=x86_64-apple-macosx -disable-lsr -post-RA-scheduler=1 -break-anti-dependencies=critical  | FileCheck %s
+
+; In PR20020, the critical anti-dependency breaker algorithm mistakenly
+; changes the register operands of an 'xorl %eax, %eax' to 'xorl %ecx, %ecx'
+; and then immediately reloads %rcx with a value based on the wrong %rax
+
+; CHECK-NOT: xorl %ecx, %ecx
+; CHECK: leaq 1(%rax), %rcx
+
+
+%struct.planet = type { double, double, double }
+
+; Function Attrs: nounwind ssp uwtable
+define void @advance(i32 %nbodies, %struct.planet* nocapture %bodies) #0 {
+entry:
+  %cmp4 = icmp sgt i32 %nbodies, 0
+  br i1 %cmp4, label %for.body.preheader, label %for.end38
+
+for.body.preheader:                               ; preds = %entry
+  %gep = getelementptr %struct.planet* %bodies, i64 1, i32 1
+  %gep13 = bitcast double* %gep to %struct.planet*
+  %0 = add i32 %nbodies, -1
+  br label %for.body
+
+for.body:                                         ; preds = %for.body.preheader, %for.inc20
+  %iv19 = phi i32 [ %0, %for.body.preheader ], [ %iv.next, %for.inc20 ]
+  %iv = phi %struct.planet* [ %gep13, %for.body.preheader ], [ %gep14, %for.inc20 ]
+  %iv9 = phi i64 [ %iv.next10, %for.inc20 ], [ 0, %for.body.preheader ]
+  %iv.next10 = add nuw nsw i64 %iv9, 1
+  %1 = trunc i64 %iv.next10 to i32
+  %cmp22 = icmp slt i32 %1, %nbodies
+  br i1 %cmp22, label %for.body3.lr.ph, label %for.inc20
+
+for.body3.lr.ph:                                  ; preds = %for.body
+  %x = getelementptr inbounds %struct.planet* %bodies, i64 %iv9, i32 0
+  %y = getelementptr inbounds %struct.planet* %bodies, i64 %iv9, i32 1
+  %vx = getelementptr inbounds %struct.planet* %bodies, i64 %iv9, i32 2
+  br label %for.body3
+
+for.body3:                                        ; preds = %for.body3, %for.body3.lr.ph
+  %iv20 = phi i32 [ %iv.next21, %for.body3 ], [ %iv19, %for.body3.lr.ph ]
+  %iv15 = phi %struct.planet* [ %gep16, %for.body3 ], [ %iv, %for.body3.lr.ph ]
+  %iv1517 = bitcast %struct.planet* %iv15 to double*
+  %2 = load double* %x, align 8
+  %gep18 = getelementptr double* %iv1517, i64 -1
+  %3 = load double* %gep18, align 8
+  %sub = fsub double %2, %3
+  %4 = load double* %y, align 8
+  %5 = load double* %iv1517, align 8
+  %sub8 = fsub double %4, %5
+  %add10 = fadd double %sub, %sub8
+  %call = tail call double @sqrt(double %sub8) #2
+  store double %add10, double* %vx, align 8
+  %gep16 = getelementptr %struct.planet* %iv15, i64 1
+  %iv.next21 = add i32 %iv20, -1
+  %exitcond = icmp eq i32 %iv.next21, 0
+  br i1 %exitcond, label %for.inc20, label %for.body3
+
+for.inc20:                                        ; preds = %for.body3, %for.body
+  %lftr.wideiv11 = trunc i64 %iv.next10 to i32
+  %gep14 = getelementptr %struct.planet* %iv, i64 1
+  %iv.next = add i32 %iv19, -1
+  %exitcond12 = icmp eq i32 %lftr.wideiv11, %nbodies
+  br i1 %exitcond12, label %for.end38, label %for.body
+
+for.end38:                                        ; preds = %for.inc20, %entry
+  ret void
+}
+
+; Function Attrs: nounwind
+declare double @sqrt(double) #1
+
+attributes #0 = { "no-frame-pointer-elim-non-leaf" }