There are 2 changes relative to the previous version of the patch:

1) For the "simple" if-conversion case, there's no need to worry about
RemoveExtraEdges not handling an unanalyzable branch.  Predicated terminators
are ignored in this context, so RemoveExtraEdges does the right thing.
This might break someday if we ever treat indirect branches (BRIND) as
predicable, but for now, I just removed this part of the patch, because
in the case where we do not add an unconditional branch, we rely on keeping
the fall-through edge to CvtBBI (which is empty after this transformation).

The change relative to the previous patch is:

@@ -1036,10 +1036,6 @@
     IterIfcvt = false;
   }
 
-  // RemoveExtraEdges won't work if the block has an unanalyzable branch,
-  // which is typically the case for IfConvertSimple, so explicitly remove
-  // CvtBBI as a successor.
-  BBI.BB->removeSuccessor(CvtBBI->BB);
   RemoveExtraEdges(BBI);
 
   // Update block info. BB can be iteratively if-converted.


2) My patch exposed a bug in the code for merging the tail of a "diamond",
which had previously never been exercised.  The code was simply checking that
the tail had a single predecessor, but there was a case in
MultiSource/Benchmarks/VersaBench/dbms where that single predecessor was
neither edge of the diamond.  I added the following change to check for
that:

@@ -1276,7 +1276,18 @@
   // tail, add a unconditional branch to it.
   if (TailBB) {
     BBInfo TailBBI = BBAnalysis[TailBB->getNumber()];
-    if (TailBB->pred_size() == 1 && !TailBBI.HasFallThrough) {
+    bool CanMergeTail = !TailBBI.HasFallThrough;
+    // There may still be a fall-through edge from BBI1 or BBI2 to TailBB;
+    // check if there are any other predecessors besides those.
+    unsigned NumPreds = TailBB->pred_size();
+    if (NumPreds > 1)
+      CanMergeTail = false;
+    else if (NumPreds == 1 && CanMergeTail) {
+      MachineBasicBlock::pred_iterator PI = TailBB->pred_begin();
+      if (*PI != BBI1->BB && *PI != BBI2->BB)
+        CanMergeTail = false;
+    }
+    if (CanMergeTail) {
       MergeBlocks(BBI, TailBBI);
       TailBBI.IsDone = true;
     } else {

With these fixes, I was able to run all the SingleSource and MultiSource
tests successfully.

llvm-svn: 107110

properly handles instructions and arguments defined in different
functions, or across recursive function iterations.

llvm-svn: 107109

llvm-svn: 107108

the same as ARM except that the condition code field is always set to ARMCC::AL.

llvm-svn: 107107

can't be changed arbitrarily by the DAGCombiner without checking if it is
running after legalization.

llvm-svn: 107097

of the Subtarget.

llvm-svn: 107086

llvm-svn: 107085

have to be registers, per gcc documentation.  This affects
the logic for determining what "g" should lower to.  PR 7393.
A couple of existing testcases are affected.

llvm-svn: 107079

llvm-svn: 107077

llvm-svn: 107074

llvm-svn: 107073

code in unreachable blocks, which have have use-def cycles.
This fixes PR7514.

llvm-svn: 107071

llvm-svn: 107070

llvm-svn: 107068

llvm-svn: 107067

llvm-svn: 107065

llvm-svn: 107060

you would expect.

Don't assert on that case, just give up.

This fixes PR7513.

llvm-svn: 107046

When an instruction has tied operands and physreg defines, we must take extra
care that the tied operands conflict with neither physreg defs nor uses.

The special treatment is given to inline asm and instructions with tied operands
/ early clobbers and physreg defines.

This fixes PR7509.

llvm-svn: 107043

llvm-svn: 107042

Remove library check and regenerate configure.

llvm-svn: 107028

Radar 8122864.

llvm-svn: 107027

llvm-svn: 107017

llvm-svn: 107016

llvm-svn: 107015

llvm-svn: 107014

interprocedurally. Note that as of this writing, existing alias
analysis passes are not prepared to be used interprocedurally.

llvm-svn: 107013

block, not...", it caused a bunch of nightly test regressions.

llvm-svn: 107009

llvm-svn: 107004

llvm-svn: 107003

llvm-svn: 107002

llvm-svn: 107000

llvm-svn: 106990

Use named MDNode, llvm.dbg.sp, to collect subprogram info. This will be used to emit  local variable's debug info of deleted functions.

llvm-svn: 106989

llvm-svn: 106988

Do not forget last element, function, while creating Subprogram definition MDNode from subprogram declare MDNode.

llvm-svn: 106985

large integers, the first inserted value would always create
an 'or X, 0'.  Even though this is trivially zapped by
instcombine, don't bother creating this pointless instruction.

llvm-svn: 106979

This produces terrible but correct code.

llvm-svn: 106952

regressions.

--- Reverse-merging r106939 into '.':
U    test/CodeGen/Thumb2/thumb2-ifcvt3.ll
U    lib/CodeGen/IfConversion.cpp

llvm-svn: 106951

the returned value after the tail call if it differs from other return
values.  The optimal thing to do would be to introduce a phi node for
the return value, but for the moment just fix the miscompile.

llvm-svn: 106947