1 files changed, 33 insertions, 10 deletions

diff --git a/contrib/llvm-project/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp b/contrib/llvm-project/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
index d975b8bd04fe..ad180cb2935e 100644
--- a/contrib/llvm-project/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
+++ b/contrib/llvm-project/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
@@ -1186,8 +1186,10 @@ bool AArch64LoadStoreOpt::findMatchingStore(
     // store instruction writes and the stored value is not modified, we can
     // promote the load. Since we do not handle stores with pre-/post-index,
     // it's unnecessary to check if BaseReg is modified by the store itself.
+    // Also we can't handle stores without an immediate offset operand,
+    // while the operand might be the address for a global variable.
     if (MI.mayStore() && isMatchingStore(LoadMI, MI) &&
-        BaseReg == getLdStBaseOp(MI).getReg() &&
+        BaseReg == getLdStBaseOp(MI).getReg() && getLdStOffsetOp(MI).isImm() &&
         isLdOffsetInRangeOfSt(LoadMI, MI, TII) &&
         ModifiedRegUnits.available(getLdStRegOp(MI).getReg())) {
       StoreI = MBBI;
@@ -1550,16 +1552,27 @@ AArch64LoadStoreOpt::findMatchingInsn(MachineBasicBlock::iterator I,
             continue;
           }
         }
-        // If the destination register of the loads is the same register, bail
-        // and keep looking. A load-pair instruction with both destination
-        // registers the same is UNPREDICTABLE and will result in an exception.
-        if (MayLoad && Reg == getLdStRegOp(MI).getReg()) {
+        // If the destination register of one load is the same register or a
+        // sub/super register of the other load, bail and keep looking. A
+        // load-pair instruction with both destination registers the same is
+        // UNPREDICTABLE and will result in an exception.
+        if (MayLoad &&
+            TRI->isSuperOrSubRegisterEq(Reg, getLdStRegOp(MI).getReg())) {
           LiveRegUnits::accumulateUsedDefed(MI, ModifiedRegUnits, UsedRegUnits,
                                             TRI);
           MemInsns.push_back(&MI);
           continue;
         }
 
+        // If the BaseReg has been modified, then we cannot do the optimization.
+        // For example, in the following pattern
+        //   ldr x1 [x2]
+        //   ldr x2 [x3]
+        //   ldr x4 [x2, #8],
+        // the first and third ldr cannot be converted to ldp x1, x4, [x2]
+        if (!ModifiedRegUnits.available(BaseReg))
+          return E;
+
         // If the Rt of the second instruction was not modified or used between
         // the two instructions and none of the instructions between the second
         // and first alias with the second, we can combine the second into the
@@ -1750,6 +1763,11 @@ bool AArch64LoadStoreOpt::isMatchingUpdateInsn(MachineInstr &MemMI,
   return false;
 }
 
+static bool needsWinCFI(const MachineFunction *MF) {
+  return MF->getTarget().getMCAsmInfo()->usesWindowsCFI() &&
+         MF->getFunction().needsUnwindTableEntry();
+}
+
 MachineBasicBlock::iterator AArch64LoadStoreOpt::findMatchingUpdateInsnForward(
     MachineBasicBlock::iterator I, int UnscaledOffset, unsigned Limit) {
   MachineBasicBlock::iterator E = I->getParent()->end();
@@ -1790,14 +1808,11 @@ MachineBasicBlock::iterator AArch64LoadStoreOpt::findMatchingUpdateInsnForward(
   // the memory access (I) and the increment (MBBI) can access the memory
   // region defined by [SP, MBBI].
   const bool BaseRegSP = BaseReg == AArch64::SP;
-  if (BaseRegSP) {
+  if (BaseRegSP && needsWinCFI(I->getMF())) {
     // FIXME: For now, we always block the optimization over SP in windows
     // targets as it requires to adjust the unwind/debug info, messing up
     // the unwind info can actually cause a miscompile.
-    const MCAsmInfo *MAI = I->getMF()->getTarget().getMCAsmInfo();
-    if (MAI->usesWindowsCFI() &&
-        I->getMF()->getFunction().needsUnwindTableEntry())
-      return E;
+    return E;
   }
 
   for (unsigned Count = 0; MBBI != E && Count < Limit;
@@ -1853,6 +1868,14 @@ MachineBasicBlock::iterator AArch64LoadStoreOpt::findMatchingUpdateInsnBackward(
     }
   }
 
+  const bool BaseRegSP = BaseReg == AArch64::SP;
+  if (BaseRegSP && needsWinCFI(I->getMF())) {
+    // FIXME: For now, we always block the optimization over SP in windows
+    // targets as it requires to adjust the unwind/debug info, messing up
+    // the unwind info can actually cause a miscompile.
+    return E;
+  }
+
   // Track which register units have been modified and used between the first
   // insn (inclusive) and the second insn.
   ModifiedRegUnits.clear();