Bulk erasing instructions without RAUWing them is unsafe. Instead, break them

into a new BB that has no predecessors.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77433 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/SimplifyLibCalls.cpp b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
index 506ba1fdb6d6e2df9b59675b532200298293aa64..14212bc5799eb63c4385b7d8a56b8b8bcbdab25e 100644 (file)
--- a/lib/Transforms/Scalar/SimplifyLibCalls.cpp
+++ b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
@@ -519,17 +519,19 @@ struct VISIBILITY_HIDDEN ExitOpt : public LibCallOptimization {
 
     TerminatorInst *OldTI = CI->getParent()->getTerminator();
     
-    // Create the return after the call.
-    ReturnInst *RI = B.CreateRet(CI->getOperand(1));
-
     // Drop all successor phi node entries.
     for (unsigned i = 0, e = OldTI->getNumSuccessors(); i != e; ++i)
       OldTI->getSuccessor(i)->removePredecessor(CI->getParent());
     
-    // Erase all instructions from after our return instruction until the end of
-    // the block.
-    BasicBlock::iterator FirstDead = RI; ++FirstDead;
-    CI->getParent()->getInstList().erase(FirstDead, CI->getParent()->end());
+    // Split the basic block after the call to exit.
+    BasicBlock::iterator FirstDead = CI; ++FirstDead;
+    CI->getParent()->splitBasicBlock(FirstDead);
+    B.SetInsertPoint(B.GetInsertBlock());
+
+    // Remove the branch that splitBB created and insert a return instead.
+    CI->getParent()->getTerminator()->eraseFromParent();
+    B.CreateRet(CI->getOperand(1));
+
     return CI;
   }
 };

diff --git a/test/Transforms/SimplifyLibCalls/2009-07-28-Exit.ll b/test/Transforms/SimplifyLibCalls/2009-07-28-Exit.ll
new file mode 100644 (file)
index 0000000..6e7440e
--- /dev/null
+++ b/test/Transforms/SimplifyLibCalls/2009-07-28-Exit.ll
@@ -0,0 +1,179 @@
+; RUN: llvm-as < %s | opt -simplify-libcalls
+; PR4641
+
+       %struct.__sFILE = type { i8*, i32, i32, i16, i16, %struct.__sbuf, i32, i8*, i32 (i8*)*, i32 (i8*, i8*, i32)*, i64 (i8*, i64, i32)*, i32 (i8*, i8*, i32)*, %struct.__sbuf, i8*, i32, [3 x i8], [1 x i8], %struct.__sbuf, i32, i64, %struct.pthread_mutex*, %struct.pthread*, i32, i32, %union.anon }
+       %struct.__sbuf = type { i8*, i32, [4 x i8] }
+       %struct.pthread = type opaque
+       %struct.pthread_mutex = type opaque
+       %union.anon = type { i64, [120 x i8] }
+@.str13 = external constant [2 x i8]           ; <[2 x i8]*> [#uses=1]
+@.str14 = external constant [2 x i8]           ; <[2 x i8]*> [#uses=1]
+
+define i32 @main(i32 %argc, i8** %argv) nounwind {
+entry:
+       br i1 undef, label %if.then.i, label %xmalloc.exit
+
+if.then.i:             ; preds = %entry
+       unreachable
+
+xmalloc.exit:          ; preds = %entry
+       br i1 undef, label %if.then.i11, label %xmalloc.exit13
+
+if.then.i11:           ; preds = %xmalloc.exit
+       unreachable
+
+xmalloc.exit13:                ; preds = %xmalloc.exit
+       br label %while.cond
+
+while.cond:            ; preds = %sw.bb124, %if.end59, %if.end, %while.cond, %xmalloc.exit13
+       switch i32 undef, label %sw.default [
+               i32 -1, label %for.cond
+               i32 0, label %while.cond
+               i32 4097, label %sw.bb36
+               i32 102, label %sw.bb55
+               i32 111, label %sw.bb55
+               i32 108, label %sw.bb62
+               i32 99, label %sw.bb84
+               i32 86, label %sw.bb114
+               i32 66, label %sw.bb124
+       ]
+
+sw.bb36:               ; preds = %while.cond
+       br i1 undef, label %if.end, label %if.then
+
+if.then:               ; preds = %sw.bb36
+       unreachable
+
+if.end:                ; preds = %sw.bb36
+       br label %while.cond
+
+sw.bb55:               ; preds = %while.cond, %while.cond
+       br i1 undef, label %if.end59, label %if.then58
+
+if.then58:             ; preds = %sw.bb55
+       br label %if.end59
+
+if.end59:              ; preds = %if.then58, %sw.bb55
+       br label %while.cond
+
+sw.bb62:               ; preds = %while.cond
+       unreachable
+
+sw.bb84:               ; preds = %while.cond
+       unreachable
+
+sw.bb114:              ; preds = %while.cond
+       unreachable
+
+sw.bb124:              ; preds = %while.cond
+       br label %while.cond
+
+sw.default:            ; preds = %while.cond
+       unreachable
+
+for.cond:              ; preds = %while.cond
+       br i1 undef, label %if.end167, label %if.then8.i
+
+if.then8.i:            ; preds = %for.cond
+       unreachable
+
+if.end167:             ; preds = %for.cond
+       br i1 undef, label %if.then174, label %if.end175
+
+if.then174:            ; preds = %if.end167
+       unreachable
+
+if.end175:             ; preds = %if.end167
+       br i1 undef, label %if.then179, label %if.end181
+
+if.then179:            ; preds = %if.end175
+       unreachable
+
+if.end181:             ; preds = %if.end175
+       br i1 undef, label %if.then.i.i189, label %while.cond.i194
+
+if.then.i.i189:                ; preds = %if.end181
+       unreachable
+
+while.cond.i194:               ; preds = %if.end181
+       br i1 undef, label %while.body.i198, label %for.cond.i.i202
+
+while.body.i198:               ; preds = %while.cond.i194
+       unreachable
+
+for.cond.i.i202:               ; preds = %while.cond.i194
+       br i1 undef, label %if.end197, label %if.then191
+
+if.then191:            ; preds = %for.cond.i.i202
+       unreachable
+
+if.end197:             ; preds = %for.cond.i.i202
+       br label %for.cond.i144
+
+for.cond.i144:         ; preds = %for.body.i145, %if.end197
+       br i1 undef, label %for.body.i145, label %for.cond24.i
+
+for.body.i145:         ; preds = %for.cond.i144
+       br label %for.cond.i144
+
+for.cond24.i:          ; preds = %for.cond.i144
+       br label %for.cond78.i
+
+for.cond78.i:          ; preds = %for.body84.i, %for.cond24.i
+       br i1 undef, label %for.end94.i, label %for.body84.i
+
+for.body84.i:          ; preds = %for.cond78.i
+       br label %for.cond78.i
+
+for.end94.i:           ; preds = %for.cond78.i
+       br i1 undef, label %if.then.i.i139, label %linebuffer_init.exit142
+
+if.then.i.i139:                ; preds = %for.end94.i
+       br label %linebuffer_init.exit142
+
+linebuffer_init.exit142:               ; preds = %if.then.i.i139, %for.end94.i
+       br i1 undef, label %if.then.i.i124, label %linebuffer_init.exit129
+
+if.then.i.i124:                ; preds = %linebuffer_init.exit142
+       unreachable
+
+linebuffer_init.exit129:               ; preds = %linebuffer_init.exit142
+       br i1 undef, label %if.then.i.i110, label %linebuffer_init.exit113
+
+if.then.i.i110:                ; preds = %linebuffer_init.exit129
+       unreachable
+
+linebuffer_init.exit113:               ; preds = %linebuffer_init.exit129
+       br i1 undef, label %if.then.i.i98, label %linebuffer_init.exit
+
+if.then.i.i98:         ; preds = %linebuffer_init.exit113
+       br label %linebuffer_init.exit
+
+linebuffer_init.exit:          ; preds = %if.then.i.i98, %linebuffer_init.exit113
+       br i1 undef, label %if.then227, label %while.cond.i50
+
+if.then227:            ; preds = %linebuffer_init.exit
+       unreachable
+
+while.cond.i50:                ; preds = %linebuffer_init.exit
+       br i1 undef, label %while.end339, label %while.body334
+
+while.body334:         ; preds = %while.cond.i50
+       unreachable
+
+while.end339:          ; preds = %while.cond.i50
+       br i1 undef, label %if.then344, label %if.end346
+
+if.then344:            ; preds = %while.end339
+       unreachable
+
+if.end346:             ; preds = %while.end339
+       call void @exit(i32 0) nounwind
+       %cond392 = select i1 undef, i8* getelementptr ([2 x i8]* @.str13, i32 0, i32 0), i8* getelementptr ([2 x i8]* @.str14, i32 0, i32 0)            ; <i8*> [#uses=1]
+       %call393 = call %struct.__sFILE* @fopen(i8* undef, i8* %cond392) nounwind               ; <%struct.__sFILE*> [#uses=0]
+       unreachable
+}
+
+declare %struct.__sFILE* @fopen(i8*, i8*)
+
+declare void @exit(i32)