[PATCH] PR16490: Fix a crash in ARM inline asm

[Joey Gouly]

In the DAG, the way immediates are constructed is with two operands, the first operand is a constant of InlineAsm::Kind_Imm, and the second is the actual immediate. (see SelectionDAGBuilder::visitInlineAsm, ~6249 of lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp).

So in 'ARMDAGToDAGISel::SelectInlineAsm', if we reach a constant with the Kind_Imm value, we need to skip the next constant. Otherwise funny things happen, because it thinks the immediate constant is actually a register use/def. It seems this was working with small, positive constants, however with the constant '-14', it was producing massive unsigned numbers and causing crashes.

Does this make sense?

http://llvm-reviews.chandlerc.com/D1084

Files:
  lib/Target/ARM/ARMISelDAGToDAG.cpp
  test/CodeGen/ARM/arm-modifier.ll

Index: lib/Target/ARM/ARMISelDAGToDAG.cpp
===================================================================
--- lib/Target/ARM/ARMISelDAGToDAG.cpp
+++ lib/Target/ARM/ARMISelDAGToDAG.cpp
@@ -3491,6 +3491,12 @@
     else
       continue;
 
+    if (Kind == InlineAsm::Kind_Imm) {
+      SDValue op = N->getOperand(++i);
+      AsmNodeOperands.push_back(op);
+      continue;
+    }
+
     unsigned NumRegs = InlineAsm::getNumOperandRegisters(Flag);
     if (NumRegs)
       OpChanged.push_back(false);
Index: test/CodeGen/ARM/arm-modifier.ll
===================================================================
--- test/CodeGen/ARM/arm-modifier.ll
+++ test/CodeGen/ARM/arm-modifier.ll
@@ -65,3 +65,8 @@
   %0 = tail call i64 asm sideeffect "ldrexd $0, ${0:H}, [$1]", "=&r,r,*Qo"(i64* %val, i64* %val) nounwind
   ret i64 %0
 }
+
+define void @f5(i64 %__pu_val) {
+  call void asm sideeffect "$1", "r,i"(i64 %__pu_val, i32 -14)
+  ret void
+}
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