diff test/Transforms/IndVarSimplify/dont-recompute.ll @ 0:95c75e76d11b LLVM3.4

LLVM 3.4
author Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
date Thu, 12 Dec 2013 13:56:28 +0900
parents
children c2174574ed3a
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line diff
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/Transforms/IndVarSimplify/dont-recompute.ll	Thu Dec 12 13:56:28 2013 +0900
@@ -0,0 +1,69 @@
+; RUN: opt < %s -indvars -S | FileCheck %s
+
+; This tests that the IV is not recomputed outside of the loop when it is known
+; to be computed by the loop and used in the loop any way. In the example below
+; although a's value can be computed outside of the loop, there is no benefit
+; in doing so as it has to be computed by the loop anyway.
+;
+; extern void func(unsigned val);
+;
+; void test(unsigned m)
+; {
+;   unsigned a = 0;
+;
+;   for (int i=0; i<186; i++) {
+;     a += m;
+;     func(a);
+;   }
+;
+;   func(a);
+; }
+
+declare void @func(i32)
+
+; CHECK-LABEL: @test(
+define void @test(i32 %m) nounwind uwtable {
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+  %i.06 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
+  %a.05 = phi i32 [ 0, %entry ], [ %add, %for.body ]
+  %add = add i32 %a.05, %m
+; CHECK: tail call void @func(i32 %add)
+  tail call void @func(i32 %add)
+  %inc = add nsw i32 %i.06, 1
+  %exitcond = icmp eq i32 %inc, 186
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body
+; CHECK: for.end:
+; CHECK-NOT: mul i32 %m, 186
+; CHECK:%add.lcssa = phi i32 [ %add, %for.body ]
+; CHECK-NEXT: tail call void @func(i32 %add.lcssa)
+  tail call void @func(i32 %add)
+  ret void
+}
+
+; CHECK-LABEL: @test2(
+define i32 @test2(i32 %m) nounwind uwtable {
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+  %i.06 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
+  %a.05 = phi i32 [ 0, %entry ], [ %add, %for.body ]
+  %add = add i32 %a.05, %m
+; CHECK: tail call void @func(i32 %add)
+  tail call void @func(i32 %add)
+  %inc = add nsw i32 %i.06, 1
+  %exitcond = icmp eq i32 %inc, 186
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body
+; CHECK: for.end:
+; CHECK-NOT: mul i32 %m, 186
+; CHECK:%add.lcssa = phi i32 [ %add, %for.body ]
+; CHECK-NEXT: ret i32 %add.lcssa
+  ret i32 %add
+}