[llvm-commits] [llvm] r61028 - in /llvm/trunk: lib/Target/README.txt test/Transforms/GVN/lpre-call-wrap.ll

[Chris Lattner]

Author: lattner
Date: Mon Dec 15 00:34:48 2008
New Revision: 61028

URL: http://llvm.org/viewvc/llvm-project?rev=61028&view=rev
Log:
gvn now hoists this load out of the hot non-call path.

Added:
    llvm/trunk/test/Transforms/GVN/lpre-call-wrap.ll
Modified:
    llvm/trunk/lib/Target/README.txt

Modified: llvm/trunk/lib/Target/README.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/README.txt?rev=61028&r1=61027&r2=61028&view=diff

==============================================================================
--- llvm/trunk/lib/Target/README.txt (original)
+++ llvm/trunk/lib/Target/README.txt Mon Dec 15 00:34:48 2008
@@ -1404,32 +1404,3 @@
 
 //===---------------------------------------------------------------------===//
 
-This C++ file:
-void g(); struct A { int n; int m; A& operator++(void) { ++n; if (n == m) g(); 
-return *this; }    A() : n(0), m(0) { } friend bool operator!=(A const& a1, 
-A const& a2) { return a1.n != a2.n; } }; void testfunction(A& iter) { A const 
-end; while (iter != end) ++iter; }
-
-Compiles down to:
-
-bb:		; preds = %bb3.backedge, %bb.nph
-	%.rle = phi i32 [ %1, %bb.nph ], [ %7, %bb3.backedge ]		; <i32> [#uses=1]
-	%4 = add i32 %.rle, 1		; <i32> [#uses=2]
-	store i32 %4, i32* %0, align 4
-	%5 = load i32* %3, align 4		; <i32> [#uses=1]
-	%6 = icmp eq i32 %4, %5		; <i1> [#uses=1]
-	br i1 %6, label %bb1, label %bb3.backedge
-
-bb1:		; preds = %bb
-	tail call void @_Z1gv()
-	br label %bb3.backedge
-
-bb3.backedge:		; preds = %bb, %bb1
-	%7 = load i32* %0, align 4		; <i32> [#uses=2]
-
-
-The %7 load is partially redundant with the store of %4 to %0, GVN's PRE 
-should remove it, but it doesn't apply to memory objects.
-
-//===---------------------------------------------------------------------===//
-

Added: llvm/trunk/test/Transforms/GVN/lpre-call-wrap.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/GVN/lpre-call-wrap.ll?rev=61028&view=auto

==============================================================================
--- llvm/trunk/test/Transforms/GVN/lpre-call-wrap.ll (added)
+++ llvm/trunk/test/Transforms/GVN/lpre-call-wrap.ll Mon Dec 15 00:34:48 2008
@@ -0,0 +1,54 @@
+; RUN: llvm-as < %s | opt -gvn -enable-load-pre | llvm-dis > %t
+; RUN: %prcontext bb3.backedge: 2 < %t | grep phi
+; RUN: %prcontext bb3.backedge: 2 < %t | not grep load
+;
+; Make sure the load in bb3.backedge is removed and moved into bb1 after the 
+; call.  This makes the non-call case faster. 
+;
+; This test is derived from this C++ code:
+; void g();
+; struct A { 
+;   int n; int m;
+;   A& operator++(void) { ++n; if (n == m) g(); return *this; }
+;   A() : n(0), m(0) { } 
+;   friend bool operator!=(A const& a1, A const& a2) { return a1.n != a2.n; }
+; };
+; void testfunction(A& iter) { A const end; while (iter != end) ++iter; }
+;
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
+target triple = "i386-apple-darwin7"
+	%struct.A = type { i32, i32 }
+
+define void @_Z12testfunctionR1A(%struct.A* %iter) {
+entry:
+	%0 = getelementptr %struct.A* %iter, i32 0, i32 0		; <i32*> [#uses=3]
+	%1 = load i32* %0, align 4		; <i32> [#uses=2]
+	%2 = icmp eq i32 %1, 0		; <i1> [#uses=1]
+	br i1 %2, label %return, label %bb.nph
+
+bb.nph:		; preds = %entry
+	%3 = getelementptr %struct.A* %iter, i32 0, i32 1		; <i32*> [#uses=1]
+	br label %bb
+
+bb:		; preds = %bb3.backedge, %bb.nph
+	%.rle = phi i32 [ %1, %bb.nph ], [ %7, %bb3.backedge ]		; <i32> [#uses=1]
+	%4 = add i32 %.rle, 1		; <i32> [#uses=2]
+	store i32 %4, i32* %0, align 4
+	%5 = load i32* %3, align 4		; <i32> [#uses=1]
+	%6 = icmp eq i32 %4, %5		; <i1> [#uses=1]
+	br i1 %6, label %bb1, label %bb3.backedge
+
+bb1:		; preds = %bb
+	tail call void @_Z1gv()
+	br label %bb3.backedge
+
+bb3.backedge:		; preds = %bb, %bb1
+	%7 = load i32* %0, align 4		; <i32> [#uses=2]
+	%8 = icmp eq i32 %7, 0		; <i1> [#uses=1]
+	br i1 %8, label %return, label %bb
+
+return:		; preds = %bb3.backedge, %entry
+	ret void
+}
+
+declare void @_Z1gv()