[FastISel][AArch64] Don't fold the 'and' instruction into the 'tbz/tbnz' instruction if it is in a different basic block.

This fixes a bug where the input register was not defined for the 'tbz/tbnz'
instruction. This happened, because we folded the 'and' instruction from a
different basic block.

This fixes rdar://problem/18784013.

llvm-svn: 220704

2 files changed, 18 insertions, 2 deletions

diff --git a/llvm/lib/Target/AArch64/AArch64FastISel.cpp b/llvm/lib/Target/AArch64/AArch64FastISel.cpp
index 1e4499b8d53..d6269284801 100644
--- a/llvm/lib/Target/AArch64/AArch64FastISel.cpp
+++ b/llvm/lib/Target/AArch64/AArch64FastISel.cpp
@@ -2118,7 +2118,7 @@ bool AArch64FastISel::emitCompareAndBranch(const BranchInst *BI) {
       return false;
 
     if (const auto *AI = dyn_cast<BinaryOperator>(LHS))
-      if (AI->getOpcode() == Instruction::And) {
+      if (AI->getOpcode() == Instruction::And && isValueAvailable(AI)) {
         const Value *AndLHS = AI->getOperand(0);
         const Value *AndRHS = AI->getOperand(1);
 
@@ -2165,7 +2165,7 @@ bool AArch64FastISel::emitCompareAndBranch(const BranchInst *BI) {
   bool Is64Bit = BW == 64;
   if (TestBit < 32 && TestBit >= 0)
     Is64Bit = false;
-  
+
   unsigned Opc = OpcTable[IsBitTest][IsCmpNE][Is64Bit];
   const MCInstrDesc &II = TII.get(Opc);
 
diff --git a/llvm/test/CodeGen/AArch64/fast-isel-tbz.ll b/llvm/test/CodeGen/AArch64/fast-isel-tbz.ll
index 9fd10cb7a47..d7f46b2cfde 100644
--- a/llvm/test/CodeGen/AArch64/fast-isel-tbz.ll
+++ b/llvm/test/CodeGen/AArch64/fast-isel-tbz.ll
@@ -121,5 +121,21 @@ bb2:
   ret i32 0
 }
 
+; Test that we don't fold the 'and' instruction into the compare.
+define i32 @icmp_eq_and_i32(i32 %a, i1 %c) {
+; CHECK-LABEL: icmp_eq_and_i32
+; CHECK:       and  [[REG:w[0-9]+]], w0, #0x4
+; CHECK-NEXT:  cbz  [[REG]], {{LBB.+_3}}
+  %1 = and i32 %a, 4
+  br i1 %c, label %bb0, label %bb2
+bb0:
+  %2 = icmp eq i32 %1, 0
+  br i1 %2, label %bb1, label %bb2, !prof !0
+bb1:
+  ret i32 1
+bb2:
+  ret i32 0
+}
+
 !0 = metadata !{metadata !"branch_weights", i32 0, i32 2147483647}
 !1 = metadata !{metadata !"branch_weights", i32 2147483647, i32 0}