[llvm-commits] [llvm] r50860 - in /llvm/trunk: lib/Transforms/Scalar/InstructionCombining.cpp test/Transforms/InstCombine/2008-05-08-StrLenSink.ll

[Chris Lattner]

Author: lattner
Date: Thu May  8 12:37:37 2008
New Revision: 50860

URL: http://llvm.org/viewvc/llvm-project?rev=50860&view=rev
Log:
More than just loads can read from memory: readonly calls like strlen
also need to be checked for memory modifying instructions before we
can sink them.  THis fixes the second half of PR2297.

Added:
    llvm/trunk/test/Transforms/InstCombine/2008-05-08-StrLenSink.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp?rev=50860&r1=50859&r2=50860&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp Thu May  8 12:37:37 2008
@@ -11229,8 +11229,8 @@
 
   // We can only sink load instructions if there is nothing between the load and
   // the end of block that could change the value.
-  if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
-    for (BasicBlock::iterator Scan = LI, E = LI->getParent()->end();
+  if (I->mayReadFromMemory()) {
+    for (BasicBlock::iterator Scan = I, E = I->getParent()->end();
          Scan != E; ++Scan)
       if (Scan->mayWriteToMemory())
         return false;
@@ -11388,8 +11388,8 @@
     }
 
     // See if we can trivially sink this instruction to a successor basic block.
-    // FIXME: Remove GetResultInst test when first class support for aggregates is
-    // implemented.
+    // FIXME: Remove GetResultInst test when first class support for aggregates
+    // is implemented.
     if (I->hasOneUse() && !isa<GetResultInst>(I)) {
       BasicBlock *BB = I->getParent();
       BasicBlock *UserParent = cast<Instruction>(I->use_back())->getParent();

Added: llvm/trunk/test/Transforms/InstCombine/2008-05-08-StrLenSink.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/2008-05-08-StrLenSink.ll?rev=50860&view=auto

==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/2008-05-08-StrLenSink.ll (added)
+++ llvm/trunk/test/Transforms/InstCombine/2008-05-08-StrLenSink.ll Thu May  8 12:37:37 2008
@@ -0,0 +1,28 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | %prcontext strlen 1 | not grep ret
+; PR2297
+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-darwin8"
+
+define i32 @a() nounwind  {
+entry:
+	%"alloca point" = bitcast i32 0 to i32		; <i32> [#uses=0]
+	%tmp1 = call i8* @malloc( i32 10 ) nounwind 		; <i8*> [#uses=5]
+	%tmp3 = getelementptr i8* %tmp1, i32 1		; <i8*> [#uses=1]
+	store i8 0, i8* %tmp3, align 1
+	%tmp5 = getelementptr i8* %tmp1, i32 0		; <i8*> [#uses=1]
+	store i8 1, i8* %tmp5, align 1
+	%tmp7 = call i32 @strlen( i8* %tmp1 ) nounwind readonly 		; <i32> [#uses=1]
+	%tmp9 = getelementptr i8* %tmp1, i32 0		; <i8*> [#uses=1]
+	store i8 0, i8* %tmp9, align 1
+	%tmp11 = call i32 (...)* @b( i8* %tmp1 ) nounwind 		; <i32> [#uses=0]
+	br label %return
+
+return:		; preds = %entry
+	ret i32 %tmp7
+}
+
+declare i8* @malloc(i32) nounwind 
+
+declare i32 @strlen(i8*) nounwind readonly 
+
+declare i32 @b(...)