[llvm-commits] [llvm] r132638 - in /llvm/trunk: lib/Transforms/Utils/SimplifyCFG.cpp test/Transforms/SimplifyCFG/indirectbr.ll

[Bill Wendling]

Author: void
Date: Sat Jun  4 04:42:04 2011
New Revision: 132638

URL: http://llvm.org/viewvc/llvm-project?rev=132638&view=rev
Log:
If the block that we're threading through is jumped to by an indirect branch,
then we don't want to set the destination in the indirect branch to the
destination. This is because the indirect branch needs its destinations to have
had their block addresses taken. This isn't so of the new critical edge that's
split during this process. If it turns out that the destination block has only
one predecessor, and that being a BB with an indirect branch, then it won't be
marked as 'used' and may be removed.
PR10072

Modified:
    llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
    llvm/trunk/test/Transforms/SimplifyCFG/indirectbr.ll

Modified: llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp?rev=132638&r1=132637&r2=132638&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp Sat Jun  4 04:42:04 2011
@@ -1171,6 +1171,8 @@
     BasicBlock *RealDest = BI->getSuccessor(!CB->getZExtValue());
     
     if (RealDest == BB) continue;  // Skip self loops.
+    // Skip if the predecessor's terminator is an indirect branch.
+    if (isa<IndirectBrInst>(PredBB->getTerminator())) continue;
     
     // The dest block might have PHI nodes, other predecessors and other
     // difficult cases.  Instead of being smart about this, just insert a new
@@ -1226,7 +1228,7 @@
         BB->removePredecessor(PredBB);
         PredBBTI->setSuccessor(i, EdgeBB);
       }
-    
+
     // Recurse, simplifying any other constants.
     return FoldCondBranchOnPHI(BI, TD) | true;
   }

Modified: llvm/trunk/test/Transforms/SimplifyCFG/indirectbr.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyCFG/indirectbr.ll?rev=132638&r1=132637&r2=132638&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/SimplifyCFG/indirectbr.ll (original)
+++ llvm/trunk/test/Transforms/SimplifyCFG/indirectbr.ll Sat Jun  4 04:42:04 2011
@@ -180,3 +180,72 @@
 ; before SimplifyCFG even looks at the indirectbr.
   indirectbr i8* %anchor, [label %L1, label %L2]
 }
+
+; PR10072
+
+ at xblkx.bbs = internal unnamed_addr constant [9 x i8*] [i8* blockaddress(@indbrtest7, %xblkx.begin), i8* blockaddress(@indbrtest7, %xblkx.begin3), i8* blockaddress(@indbrtest7, %xblkx.begin4), i8* blockaddress(@indbrtest7, %xblkx.begin5), i8* blockaddress(@indbrtest7, %xblkx.begin6), i8* blockaddress(@indbrtest7, %xblkx.begin7), i8* blockaddress(@indbrtest7, %xblkx.begin8), i8* blockaddress(@indbrtest7, %xblkx.begin9), i8* blockaddress(@indbrtest7, %xblkx.end)]
+
+define void @indbrtest7() {
+escape-string.top:
+  %xval202x = call i32 @xfunc5x()
+  br label %xlab5x
+
+xlab8x:                                           ; preds = %xlab5x
+  %xvaluex = call i32 @xselectorx()
+  %xblkx.x = getelementptr [9 x i8*]* @xblkx.bbs, i32 0, i32 %xvaluex
+  %xblkx.load = load i8** %xblkx.x
+  indirectbr i8* %xblkx.load, [label %xblkx.begin, label %xblkx.begin3, label %xblkx.begin4, label %xblkx.begin5, label %xblkx.begin6, label %xblkx.begin7, label %xblkx.begin8, label %xblkx.begin9, label %xblkx.end]
+
+xblkx.begin:
+  br label %xblkx.end
+
+xblkx.begin3:
+  br label %xblkx.end
+
+xblkx.begin4:
+  br label %xblkx.end
+
+xblkx.begin5:
+  br label %xblkx.end
+
+xblkx.begin6:
+  br label %xblkx.end
+
+xblkx.begin7:
+  br label %xblkx.end
+
+xblkx.begin8:
+  br label %xblkx.end
+
+xblkx.begin9:
+  br label %xblkx.end
+
+xblkx.end:
+  %yes.0 = phi i1 [ false, %xblkx.begin ], [ true, %xlab8x ], [ false, %xblkx.begin9 ], [ false, %xblkx.begin8 ], [ false, %xblkx.begin7 ], [ false, %xblkx.begin6 ], [ false, %xblkx.begin5 ], [ true, %xblkx.begin4 ], [ false, %xblkx.begin3 ]
+  br i1 %yes.0, label %v2j, label %xlab17x
+
+v2j:
+; CHECK: %xunusedx = call i32 @xactionx()
+  %xunusedx = call i32 @xactionx()
+  br label %xlab4x
+
+xlab17x:
+  br label %xlab4x
+
+xlab4x:
+  %incr19 = add i32 %xval704x.0, 1
+  br label %xlab5x
+
+xlab5x:
+  %xval704x.0 = phi i32 [ 0, %escape-string.top ], [ %incr19, %xlab4x ]
+  %xval10x = icmp ult i32 %xval704x.0, %xval202x
+  br i1 %xval10x, label %xlab8x, label %xlab9x
+
+xlab9x:
+  ret void
+}
+
+declare i32 @xfunc5x()
+declare i8 @xfunc7x()
+declare i32 @xselectorx()
+declare i32 @xactionx()