[llvm-commits] [llvm] r119683 - in /llvm/trunk: lib/Transforms/Scalar/ScalarReplAggregates.cpp test/Transforms/ScalarRepl/memcpy-from-global.ll

[Chris Lattner]

Author: lattner
Date: Thu Nov 18 00:26:49 2010
New Revision: 119683

URL: http://llvm.org/viewvc/llvm-project?rev=119683&view=rev
Log:
enhance the "alloca is just a memcpy from constant global"
to ignore calls that obviously can't modify the alloca
because they are readonly/readnone.

Modified:
    llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp
    llvm/trunk/test/Transforms/ScalarRepl/memcpy-from-global.ll

Modified: llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp?rev=119683&r1=119682&r2=119683&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp Thu Nov 18 00:26:49 2010
@@ -34,6 +34,7 @@
 #include "llvm/Target/TargetData.h"
 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
 #include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Support/CallSite.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/GetElementPtrTypeIterator.h"
@@ -1810,6 +1811,12 @@
       continue;
     }
     
+    // If this is a readonly/readnone call site, then we know it is just a load
+    // and we can ignore it.
+    if (CallSite CS = U)
+      if (CS.onlyReadsMemory())
+        continue;
+    
     // If this is isn't our memcpy/memmove, reject it as something we can't
     // handle.
     MemTransferInst *MI = dyn_cast<MemTransferInst>(U);

Modified: llvm/trunk/test/Transforms/ScalarRepl/memcpy-from-global.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ScalarRepl/memcpy-from-global.ll?rev=119683&r1=119682&r2=119683&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/ScalarRepl/memcpy-from-global.ll (original)
+++ llvm/trunk/test/Transforms/ScalarRepl/memcpy-from-global.ll Thu Nov 18 00:26:49 2010
@@ -68,3 +68,16 @@
 }
 
 declare void @bar(i8*)
+
+
+;; Should be able to eliminate the alloca.
+define void @test3() {
+  %A = alloca %T
+  %a = bitcast %T* %A to i8*
+  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %a, i8* bitcast (%T* @G to i8*), i64 124, i32 4, i1 false)
+  call void @bar(i8* %a) readonly
+; CHECK: @test3
+; CHECK-NEXT: %a = bitcast %T* @G to i8*
+; CHECK-NEXT: call void @bar(i8* %a)
+  ret void
+}