Nasty bug in ARMBaseInstrInfo::produceSameValue(). The MachineConstantPoolEntry

entries being compared may not be ARMConstantPoolValue. Without checking
whether they are ARMConstantPoolValue first, and if the stars and moons
are aligned properly, the equality test may return true (when the first few
words of two Constants' values happen to be identical) and very bad things can
happen.

rdar://9125354

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128203 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/ARM/ARMBaseInstrInfo.cpp b/lib/Target/ARM/ARMBaseInstrInfo.cpp
index b5f20a4402189242be5b1975a1222e72aaf0e93c..a2748225a4c2dc1fdc700b2abdb55b970d5c7c80 100644 (file)
--- a/lib/Target/ARM/ARMBaseInstrInfo.cpp
+++ b/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -1080,11 +1080,18 @@ bool ARMBaseInstrInfo::produceSameValue(const MachineInstr *MI0,
     int CPI1 = MO1.getIndex();
     const MachineConstantPoolEntry &MCPE0 = MCP->getConstants()[CPI0];
     const MachineConstantPoolEntry &MCPE1 = MCP->getConstants()[CPI1];
-    ARMConstantPoolValue *ACPV0 =
-      static_cast<ARMConstantPoolValue*>(MCPE0.Val.MachineCPVal);
-    ARMConstantPoolValue *ACPV1 =
-      static_cast<ARMConstantPoolValue*>(MCPE1.Val.MachineCPVal);
-    return ACPV0->hasSameValue(ACPV1);
+    bool isARMCP0 = MCPE0.isMachineConstantPoolEntry();
+    bool isARMCP1 = MCPE1.isMachineConstantPoolEntry();
+    if (isARMCP0 && isARMCP1) {
+      ARMConstantPoolValue *ACPV0 =
+        static_cast<ARMConstantPoolValue*>(MCPE0.Val.MachineCPVal);
+      ARMConstantPoolValue *ACPV1 =
+        static_cast<ARMConstantPoolValue*>(MCPE1.Val.MachineCPVal);
+      return ACPV0->hasSameValue(ACPV1);
+    } else if (!isARMCP0 && !isARMCP1) {
+      return MCPE0.Val.ConstVal == MCPE1.Val.ConstVal;
+    }
+    return false;
   } else if (Opcode == ARM::PICLDR) {
     if (MI1->getOpcode() != Opcode)
       return false;