From 019195229693c1829e6ed5a3f57209728fdcba8f Mon Sep 17 00:00:00 2001
From: Evan Cheng <evan.cheng@apple.com>
Date: Tue, 15 Mar 2011 18:41:52 +0000
Subject: [PATCH] Do not form thumb2 ldrd / strd if the offset is by multiple
 of 4. rdar://9133587

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127683 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/ARM/ARMLoadStoreOptimizer.cpp      | 12 +---
 .../CodeGen/ARM/2011-03-15-LdStMultipleBug.ll | 55 +++++++++++++++++++
 2 files changed, 58 insertions(+), 9 deletions(-)
 create mode 100644 test/CodeGen/ARM/2011-03-15-LdStMultipleBug.ll

diff --git a/lib/Target/ARM/ARMLoadStoreOptimizer.cpp b/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
index d9dc5cdedb3..23e0788a06e 100644
--- a/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
+++ b/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
@@ -1530,15 +1530,9 @@ ARMPreAllocLoadStoreOpt::CanFormLdStDWord(MachineInstr *Op0, MachineInstr *Op1,
   // Then make sure the immediate offset fits.
   int OffImm = getMemoryOpOffset(Op0);
   if (isT2) {
-    if (OffImm < 0) {
-      if (OffImm < -255)
-        // Can't fall back to t2LDRi8 / t2STRi8.
-        return false;
-    } else {
-      int Limit = (1 << 8) * Scale;
-      if (OffImm >= Limit || (OffImm & (Scale-1)))
-        return false;
-    }
+    int Limit = (1 << 8) * Scale;
+    if (OffImm >= Limit || (OffImm <= -Limit) || (OffImm & (Scale-1)))
+      return false;
     Offset = OffImm;
   } else {
     ARM_AM::AddrOpc AddSub = ARM_AM::add;
diff --git a/test/CodeGen/ARM/2011-03-15-LdStMultipleBug.ll b/test/CodeGen/ARM/2011-03-15-LdStMultipleBug.ll
new file mode 100644
index 00000000000..ccda281e901
--- /dev/null
+++ b/test/CodeGen/ARM/2011-03-15-LdStMultipleBug.ll
@@ -0,0 +1,55 @@
+; RUN: llc < %s -mtriple=thumbv7-apple-darwin10 -relocation-model=pic -disable-fp-elim -mcpu=cortex-a8 | FileCheck %s
+
+; Do not form Thumb2 ldrd / strd if the offset is not multiple of 4.
+; rdar://9133587
+
+%struct.Outer = type { i32, [2 x %"struct.Outer::Inner"] }
+%"struct.Outer::Inner" = type { i32, i32, i8, i8 }
+
+@oStruct = external global %struct.Outer, align 4
+
+define void @main() nounwind {
+; CHECK: main:
+; CHECK-NOT: ldrd
+; CHECK: mul
+for.body.lr.ph:
+  br label %for.body
+
+for.body:                                         ; preds = %_Z14printIsNotZeroi.exit17.for.body_crit_edge, %for.body.lr.ph
+  %tmp3 = phi i1 [ false, %for.body.lr.ph ], [ %phitmp27, %_Z14printIsNotZeroi.exit17.for.body_crit_edge ]
+  %i.022 = phi i32 [ 0, %for.body.lr.ph ], [ %inc, %_Z14printIsNotZeroi.exit17.for.body_crit_edge ]
+  %x = getelementptr %struct.Outer* @oStruct, i32 0, i32 1, i32 %i.022, i32 0
+  %y = getelementptr %struct.Outer* @oStruct, i32 0, i32 1, i32 %i.022, i32 1
+  %inc = add i32 %i.022, 1
+  br i1 %tmp3, label %_Z14printIsNotZeroi.exit, label %if.then.i
+
+if.then.i:                                        ; preds = %for.body
+  unreachable
+
+_Z14printIsNotZeroi.exit:                         ; preds = %for.body
+  %tmp8 = load i32* %x, align 4, !tbaa !0
+  %tmp11 = load i32* %y, align 4, !tbaa !0
+  %mul = mul nsw i32 %tmp11, %tmp8
+  %tobool.i14 = icmp eq i32 %mul, 0
+  br i1 %tobool.i14, label %_Z14printIsNotZeroi.exit17, label %if.then.i16
+
+if.then.i16:                                      ; preds = %_Z14printIsNotZeroi.exit
+  unreachable
+
+_Z14printIsNotZeroi.exit17:                       ; preds = %_Z14printIsNotZeroi.exit
+  br i1 undef, label %_Z14printIsNotZeroi.exit17.for.body_crit_edge, label %for.end
+
+_Z14printIsNotZeroi.exit17.for.body_crit_edge:    ; preds = %_Z14printIsNotZeroi.exit17
+  %b.phi.trans.insert = getelementptr %struct.Outer* @oStruct, i32 0, i32 1, i32 %inc, i32 3
+  %tmp3.pre = load i8* %b.phi.trans.insert, align 1, !tbaa !3
+  %phitmp27 = icmp eq i8 undef, 0
+  br label %for.body
+
+for.end:                                          ; preds = %_Z14printIsNotZeroi.exit17
+  ret void
+}
+
+!0 = metadata !{metadata !"int", metadata !1}
+!1 = metadata !{metadata !"omnipotent char", metadata !2}
+!2 = metadata !{metadata !"Simple C/C++ TBAA", null}
+!3 = metadata !{metadata !"bool", metadata !1}