From 51dee24ca6ba63cf021d56ca9cbae62c739d5041 Mon Sep 17 00:00:00 2001
From: Andrew Trick <atrick@apple.com>
Date: Tue, 15 Oct 2013 03:39:43 +0000
Subject: Improve on r192635, ExeDepsFix for avx, and add a test case.

rdar:15221834 False AVX register dependencies cause 5x slowdown on
flops-5/6 and significant slowdown on several others.

This was blocking the switch to MI-Sched.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192669 91177308-0d34-0410-b5e6-96231b3b80d8
---
 test/CodeGen/X86/break-avx-dep.ll | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)
 create mode 100644 test/CodeGen/X86/break-avx-dep.ll

(limited to 'test/CodeGen/X86')

diff --git a/test/CodeGen/X86/break-avx-dep.ll b/test/CodeGen/X86/break-avx-dep.ll
new file mode 100644
index 0000000000..eea7d1565d
--- /dev/null
+++ b/test/CodeGen/X86/break-avx-dep.ll
@@ -0,0 +1,29 @@
+; RUN: llc < %s -march=x86-64 -mattr=+avx | FileCheck %s
+;
+; rdar:15221834 False AVX register dependencies cause 5x slowdown on
+; flops-6. Make sure the unused register read by vcvtsi2sdq is zeroed
+; to avoid cyclic dependence on a write to the same register in a
+; previous iteration.
+
+; CHECK-LABEL: t1:
+; CHECK-LABEL: %loop
+; CHECK: vxorps %[[REG:xmm.]], %{{xmm.}}, %{{xmm.}}
+; CHECK: vcvtsi2sdq %{{r..}}, %[[REG]], %{{xmm.}}
+define i64 @t1(i64* nocapture %x, double* nocapture %y) nounwind {
+entry:
+  %vx = load i64* %x
+  br label %loop
+loop:
+  %i = phi i64 [ 1, %entry ], [ %inc, %loop ]
+  %s1 = phi i64 [ %vx, %entry ], [ %s2, %loop ]
+  %fi = sitofp i64 %i to double
+  %vy = load double* %y
+  %fipy = fadd double %fi, %vy
+  %iipy = fptosi double %fipy to i64
+  %s2 = add i64 %s1, %iipy
+  %inc = add nsw i64 %i, 1
+  %exitcond = icmp eq i64 %inc, 156250000
+  br i1 %exitcond, label %ret, label %loop
+ret:
+  ret i64 %s2
+}
-- 
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