pr6480: Don't try producing ld/st-multiple instructions when the address is

an undef value.  This is only going to come up for bugpoint-reduced tests --
correct programs will not access memory at undefined addresses -- so it's not
worth the effort of doing anything more aggressive.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97745 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 59 insertions, 0 deletions

diff --git a/lib/Target/ARM/ARMLoadStoreOptimizer.cpp b/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
index 5b4f02d6b7..19f1e3ba12 100644
--- a/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
+++ b/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
@@ -761,6 +761,11 @@ static bool isMemoryOp(const MachineInstr *MI) {
       MI->getOperand(0).isUndef())
     return false;
 
+  // Likewise don't mess with references to undefined addresses.
+  if (MI->getNumOperands() > 1 && MI->getOperand(1).isReg() &&
+      MI->getOperand(1).isUndef())
+    return false;
+
   int Opcode = MI->getOpcode();
   switch (Opcode) {
   default: break;
diff --git a/test/CodeGen/ARM/2010-03-04-stm-undef-addr.ll b/test/CodeGen/ARM/2010-03-04-stm-undef-addr.ll
new file mode 100644
index 0000000000..b0b4cb37d1
--- /dev/null
+++ b/test/CodeGen/ARM/2010-03-04-stm-undef-addr.ll
@@ -0,0 +1,54 @@
+; RUN: llc < %s -march=arm
+
+define void @"java.lang.String::getChars"([84 x i8]* %method, i32 %base_pc, [788 x i8]* %thread) {
+  %1 = sub i32 undef, 48                          ; <i32> [#uses=1]
+  br i1 undef, label %stack_overflow, label %no_overflow
+
+stack_overflow:                                   ; preds = %0
+  unreachable
+
+no_overflow:                                      ; preds = %0
+  %frame = inttoptr i32 %1 to [17 x i32]*         ; <[17 x i32]*> [#uses=4]
+  %2 = load i32* null                             ; <i32> [#uses=2]
+  %3 = getelementptr inbounds [17 x i32]* %frame, i32 0, i32 14 ; <i32*> [#uses=1]
+  %4 = load i32* %3                               ; <i32> [#uses=2]
+  %5 = load [8 x i8]** undef                      ; <[8 x i8]*> [#uses=2]
+  br i1 undef, label %bci_13, label %bci_4
+
+bci_13:                                           ; preds = %no_overflow
+  br i1 undef, label %bci_30, label %bci_21
+
+bci_30:                                           ; preds = %bci_13
+  %6 = icmp sle i32 %2, %4                        ; <i1> [#uses=1]
+  br i1 %6, label %bci_46, label %bci_35
+
+bci_46:                                           ; preds = %bci_30
+  store [84 x i8]* %method, [84 x i8]** undef
+  br i1 false, label %no_exception, label %exception
+
+exception:                                        ; preds = %bci_46
+  ret void
+
+no_exception:                                     ; preds = %bci_46
+  ret void
+
+bci_35:                                           ; preds = %bci_30
+  %7 = getelementptr inbounds [17 x i32]* %frame, i32 0, i32 15 ; <i32*> [#uses=1]
+  store i32 %2, i32* %7
+  %8 = getelementptr inbounds [17 x i32]* %frame, i32 0, i32 14 ; <i32*> [#uses=1]
+  store i32 %4, i32* %8
+  %9 = getelementptr inbounds [17 x i32]* %frame, i32 0, i32 13 ; <i32*> [#uses=1]
+  %10 = bitcast i32* %9 to [8 x i8]**             ; <[8 x i8]**> [#uses=1]
+  store [8 x i8]* %5, [8 x i8]** %10
+  call void inttoptr (i32 13839116 to void ([788 x i8]*, i32)*)([788 x i8]* %thread, i32 7)
+  ret void
+
+bci_21:                                           ; preds = %bci_13
+  ret void
+
+bci_4:                                            ; preds = %no_overflow
+  store [8 x i8]* %5, [8 x i8]** undef
+  store i32 undef, i32* undef
+  call void inttoptr (i32 13839116 to void ([788 x i8]*, i32)*)([788 x i8]* %thread, i32 7)
+  ret void
+}