Look through phi nodes and select instructions when

calculating nocapture attributes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61535 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/IPO/FunctionAttrs.cpp b/lib/Transforms/IPO/FunctionAttrs.cpp
index 1824a710c5155e0f861353707fb43eb1121f82c6..52be0c906e1d09e1ec1b498efb914fa3224f9fee 100644 (file)
--- a/lib/Transforms/IPO/FunctionAttrs.cpp
+++ b/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -225,9 +225,14 @@ bool FunctionAttrs::isCaptured(Function &F, Value *V) {
       continue;
     }
 
-    if (isa<BitCastInst>(I) || isa<GetElementPtrInst>(I)) {
-      // Type conversion or calculating an offset.  Does not escape if the new
-      // value doesn't.
+    if (isa<BitCastInst>(I) || isa<GetElementPtrInst>(I) ||
+        isa<PHINode>(I) || isa<SelectInst>(I)) {
+      // Type conversion, calculating an offset, or merging values.
+      // The original value does not escape via this if the new value doesn't.
+      // Note that in the case of a select instruction it is important that
+      // the value not be used as the condition, since otherwise one bit of
+      // information might escape.  It cannot be the condition because it has
+      // the wrong type.
       for (Instruction::use_iterator UI = I->use_begin(), UE = I->use_end();
            UI != UE; ++UI) {
         Use *U = &UI.getUse();

diff --git a/test/Transforms/FunctionAttrs/2008-12-31-NoCapture.ll b/test/Transforms/FunctionAttrs/2008-12-31-NoCapture.ll
index 6d2ca1e446fcd950ba54ab43cb9f977212dacc9d..86feb4318c6b0a5757e6bfde64042acd1cb8d2fe 100644 (file)
--- a/test/Transforms/FunctionAttrs/2008-12-31-NoCapture.ll
+++ b/test/Transforms/FunctionAttrs/2008-12-31-NoCapture.ll
@@ -1,34 +1,41 @@
-; RUN: llvm-as < %s | opt -functionattrs | llvm-dis | not grep {@c.*nocapture}
-; RUN: llvm-as < %s | opt -functionattrs | llvm-dis | grep nocapture | count 3
+; RUN: llvm-as < %s | opt -functionattrs | llvm-dis | not grep {nocapture *%%q}
+; RUN: llvm-as < %s | opt -functionattrs | llvm-dis | grep {nocapture *%%p} | count 3
 @g = global i32* null          ; <i32**> [#uses=1]
 
-define i32* @c1(i32* %p) {
-       ret i32* %p
+define i32* @c1(i32* %q) {
+       ret i32* %q
 }
 
-define void @c2(i32* %p) {
-       store i32* %p, i32** @g
+define void @c2(i32* %q) {
+       store i32* %q, i32** @g
        ret void
 }
 
-define void @c3(i32* %p) {
-       call void @c2(i32* %p)
+define void @c3(i32* %q) {
+       call void @c2(i32* %q)
        ret void
 }
 
-define i32 @nc1(i32* %p) {
-       %tmp = bitcast i32* %p to i32*          ; <i32*> [#uses=2]
-       %val = load i32* %tmp           ; <i32> [#uses=1]
+define i32 @nc1(i32* %q, i32* %p, i1 %b) {
+e:
+       br label %l
+l:
+       %x = phi i32* [ %p, %e ]
+       %y = phi i32* [ %q, %e ]
+       %tmp = bitcast i32* %x to i32*          ; <i32*> [#uses=2]
+       %tmp2 = select i1 %b, i32* %tmp, i32* %y
+       %val = load i32* %tmp2          ; <i32> [#uses=1]
        store i32 0, i32* %tmp
+       store i32* %y, i32** @g
        ret i32 %val
 }
 
-define void @nc2(i32* %p) {
-       %1 = call i32 @nc1(i32* %p)             ; <i32> [#uses=0]
+define void @nc2(i32* %p, i32* %q) {
+       %1 = call i32 @nc1(i32* %q, i32* %p, i1 0)              ; <i32> [#uses=0]
        ret void
 }
 
-define void @nc3(void ()* %f) {
-       call void %f()
+define void @nc3(void ()* %p) {
+       call void %p()
        ret void
 }