[llvm-commits] [llvm] r75642 - in /llvm/trunk: lib/Transforms/Scalar/SimplifyCFGPass.cpp test/Transforms/SimplifyCFG/2009-07-13-no-delete-asm.ll

[Dale Johannesen]

Author: johannes
Date: Tue Jul 14 12:48:25 2009
New Revision: 75642

URL: http://llvm.org/viewvc/llvm-project?rev=75642&view=rev
Log:
Revert 75571; I'm convinced this isn't the right thing to do.


Removed:
    llvm/trunk/test/Transforms/SimplifyCFG/2009-07-13-no-delete-asm.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/SimplifyCFGPass.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/SimplifyCFGPass.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SimplifyCFGPass.cpp?rev=75642&r1=75641&r2=75642&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/SimplifyCFGPass.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/SimplifyCFGPass.cpp Tue Jul 14 12:48:25 2009
@@ -109,8 +109,6 @@
     if (!Reachable.insert(BB))
       continue;
 
-    bool AsmFound = false;
-    StoreInst *UndefStore = 0;
     // Do a quick scan of the basic block, turning any obviously unreachable
     // instructions into LLVM unreachable insts.  The instruction combining pass
     // canonicalizes unreachable insts into stores to null or undef.
@@ -127,27 +125,20 @@
           }
           break;
         }
-        if (isa<InlineAsm>(CI->getOperand(0)))
-          AsmFound = true;
       }
       
       if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) {
         Value *Ptr = SI->getOperand(1);
-
-        if ((isa<UndefValue>(Ptr) ||
-             (isa<ConstantPointerNull>(Ptr) &&
-              cast<PointerType>(Ptr->getType())->getAddressSpace() == 0)) &&
-            !UndefStore)
-          UndefStore = SI;
+        
+        if (isa<UndefValue>(Ptr) ||
+            (isa<ConstantPointerNull>(Ptr) &&
+             cast<PointerType>(Ptr->getType())->getAddressSpace() == 0)) {
+          ChangeToUnreachable(SI, Context);
+          Changed = true;
+          break;
+        }
       }
     }
-    // We can't delete asm's just because their inputs are undefined;
-    // xor R, R is a common idiom for zeroing a register, for example.
-    // Assume user knows what he is doing.
-    if (UndefStore && !AsmFound) {
-      ChangeToUnreachable(UndefStore, Context);
-      Changed = true;
-    }
 
     // Turn invokes that call 'nounwind' functions into ordinary calls.
     if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator()))

Removed: llvm/trunk/test/Transforms/SimplifyCFG/2009-07-13-no-delete-asm.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyCFG/2009-07-13-no-delete-asm.ll?rev=75641&view=auto

==============================================================================
--- llvm/trunk/test/Transforms/SimplifyCFG/2009-07-13-no-delete-asm.ll (original)
+++ llvm/trunk/test/Transforms/SimplifyCFG/2009-07-13-no-delete-asm.ll (removed)
@@ -1,11 +0,0 @@
-; RUN: llvm-as < %s | opt -simplifycfg | llvm-dis | grep xor
-; ModuleID = '<stdin>'
-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-darwin9.6"
-
-define void @bar() nounwind {
-entry:
-	store i16 undef, i16* null
-	%asmtmp = call i32 asm sideeffect "xor $0, $0", "=={bx},rm,~{dirflag},~{fpsr},~{flags},~{memory}"(i16 undef) nounwind		; <i32> [#uses=0]
-	ret void
-}