From 8b7ab4ba2ba90341daf95adc745a54189f805c3b Mon Sep 17 00:00:00 2001
From: Preston Gurd <preston.gurd@intel.com>
Date: Thu, 25 Apr 2013 20:29:37 +0000
Subject: This patch adds the X86FixupLEAs pass, which will reduce instruction
 latency for certain models of the Intel Atom family, by converting
 instructions into their equivalent LEA instructions, when it is both useful
 and possible to do so.

llvm-svn: 180573
---
 llvm/test/CodeGen/X86/atom-fixup-lea3.ll | 51 ++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 llvm/test/CodeGen/X86/atom-fixup-lea3.ll

(limited to 'llvm/test/CodeGen/X86/atom-fixup-lea3.ll')

diff --git a/llvm/test/CodeGen/X86/atom-fixup-lea3.ll b/llvm/test/CodeGen/X86/atom-fixup-lea3.ll
new file mode 100644
index 00000000000..311b0b30216
--- /dev/null
+++ b/llvm/test/CodeGen/X86/atom-fixup-lea3.ll
@@ -0,0 +1,51 @@
+; RUN: llc < %s -mcpu=atom -mtriple=i686-linux | FileCheck %s
+; CHECK: addl ([[reg:%[a-z]+]])
+; CHECK-NEXT: addl $4, [[reg]]
+
+; Test for the FixupLEAs pre-emit pass.
+; An LEA should NOT be substituted for the ADD instruction
+; that increments the array pointer if it is greater than 5 instructions
+; away from the memory reference that uses it.
+
+; Original C code: clang -m32 -S -O2
+;int test(int n, int * array, int * m, int * array2)
+;{
+;  int i, j = 0;
+;  int sum = 0;
+;  for (i = 0, j = 0; i < n;) {
+;    ++i;
+;    *m += array2[j++];
+;    sum += array[i];
+;  }
+;  return sum;
+;}
+
+define i32 @test(i32 %n, i32* nocapture %array, i32* nocapture %m, i32* nocapture %array2) #0 {
+entry:
+  %cmp7 = icmp sgt i32 %n, 0
+  br i1 %cmp7, label %for.body.lr.ph, label %for.end
+
+for.body.lr.ph:                                   ; preds = %entry
+  %.pre = load i32* %m, align 4
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %for.body.lr.ph
+  %0 = phi i32 [ %.pre, %for.body.lr.ph ], [ %add, %for.body ]
+  %sum.010 = phi i32 [ 0, %for.body.lr.ph ], [ %add3, %for.body ]
+  %j.09 = phi i32 [ 0, %for.body.lr.ph ], [ %inc1, %for.body ]
+  %inc1 = add nsw i32 %j.09, 1
+  %arrayidx = getelementptr inbounds i32* %array2, i32 %j.09
+  %1 = load i32* %arrayidx, align 4
+  %add = add nsw i32 %0, %1
+  store i32 %add, i32* %m, align 4
+  %arrayidx2 = getelementptr inbounds i32* %array, i32 %inc1
+  %2 = load i32* %arrayidx2, align 4
+  %add3 = add nsw i32 %2, %sum.010
+  %exitcond = icmp eq i32 %inc1, %n
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body, %entry
+  %sum.0.lcssa = phi i32 [ 0, %entry ], [ %add3, %for.body ]
+  ret i32 %sum.0.lcssa
+}
+
-- 
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