Add workaround for Cortex-M3 errata 602117 by replacing ldrd x, y, [x] with ldm or ldr pairs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@144123 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 21 insertions, 14 deletions

diff --git a/lib/Target/ARM/ARMLoadStoreOptimizer.cpp b/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
index faa8ba7684..a871ed7d44 100644
--- a/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
+++ b/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
@@ -62,6 +62,7 @@ namespace {
 
     const TargetInstrInfo *TII;
     const TargetRegisterInfo *TRI;
+    const ARMSubtarget *STI;
     ARMFunctionInfo *AFI;
     RegScavenger *RS;
     bool isThumb2;
@@ -1071,11 +1072,17 @@ bool ARMLoadStoreOpt::FixInvalidRegPairOp(MachineBasicBlock &MBB,
   unsigned Opcode = MI->getOpcode();
   if (Opcode == ARM::LDRD || Opcode == ARM::STRD ||
       Opcode == ARM::t2LDRDi8 || Opcode == ARM::t2STRDi8) {
+    const MachineOperand &BaseOp = MI->getOperand(2);
+    unsigned BaseReg = BaseOp.getReg();
     unsigned EvenReg = MI->getOperand(0).getReg();
     unsigned OddReg  = MI->getOperand(1).getReg();
     unsigned EvenRegNum = TRI->getDwarfRegNum(EvenReg, false);
     unsigned OddRegNum  = TRI->getDwarfRegNum(OddReg, false);
-    if ((EvenRegNum & 1) == 0 && (EvenRegNum + 1) == OddRegNum)
+    // ARM errata 602117: LDRD with base in list may result in incorrect base
+    // register when interrupted or faulted.
+    bool Errata602117 = EvenReg == BaseReg && STI->getCPUString() == "cortex-m3";
+    if (!Errata602117 &&
+        ((EvenRegNum & 1) == 0 && (EvenRegNum + 1) == OddRegNum))
       return false;
 
     MachineBasicBlock::iterator NewBBI = MBBI;
@@ -1087,8 +1094,6 @@ bool ARMLoadStoreOpt::FixInvalidRegPairOp(MachineBasicBlock &MBB,
     bool OddDeadKill  = isLd ?
       MI->getOperand(1).isDead() : MI->getOperand(1).isKill();
     bool OddUndef = MI->getOperand(1).isUndef();
-    const MachineOperand &BaseOp = MI->getOperand(2);
-    unsigned BaseReg = BaseOp.getReg();
     bool BaseKill = BaseOp.isKill();
     bool BaseUndef = BaseOp.isUndef();
     bool OffKill = isT2 ? false : MI->getOperand(3).isKill();
@@ -1380,6 +1385,7 @@ bool ARMLoadStoreOpt::runOnMachineFunction(MachineFunction &Fn) {
   AFI = Fn.getInfo<ARMFunctionInfo>();
   TII = TM.getInstrInfo();
   TRI = TM.getRegisterInfo();
+  STI = &TM.getSubtarget<ARMSubtarget>();
   RS = new RegScavenger();
   isThumb2 = AFI->isThumb2Function();
 
diff --git a/test/CodeGen/ARM/ldrd.ll b/test/CodeGen/ARM/ldrd.ll
index 8010f20689..d72e9bfc1d 100644
--- a/test/CodeGen/ARM/ldrd.ll
+++ b/test/CodeGen/ARM/ldrd.ll
@@ -1,21 +1,22 @@
-; RUN: llc < %s -mtriple=armv6-apple-darwin -regalloc=linearscan | FileCheck %s -check-prefix=V6
-; RUN: llc < %s -mtriple=armv5-apple-darwin -regalloc=linearscan | FileCheck %s -check-prefix=V5
-; RUN: llc < %s -mtriple=armv6-eabi -regalloc=linearscan | FileCheck %s -check-prefix=EABI
-; rdar://r6949835
+; RUN: llc < %s -mtriple=thumbv7-apple-ios -mcpu=cortex-a8 -regalloc=fast | FileCheck %s -check-prefix=A8
+; RUN: llc < %s -mtriple=thumbv7-apple-ios -mcpu=cortex-m3 -regalloc=fast | FileCheck %s -check-prefix=M3
+; rdar://6949835
 
-; Magic ARM pair hints works best with linearscan.
+; Magic ARM pair hints works best with linearscan / fast.
+
+; Cortex-M3 errata 602117: LDRD with base in list may result in incorrect base
+; register when interrupted or faulted.
 
 @b = external global i64*
 
 define i64 @t(i64 %a) nounwind readonly {
 entry:
-;V6:   ldrd r2, r3, [r2]
-
-;V5:   ldr r{{[0-9]+}}, [r2]
-;V5:   ldr r{{[0-9]+}}, [r2, #4]
+; A8: t:
+; A8:   ldrd r2, r3, [r2]
 
-;EABI: ldr r{{[0-9]+}}, [r2]
-;EABI: ldr r{{[0-9]+}}, [r2, #4]
+; M3: t:
+; M3-NOT: ldrd
+; M3: ldm.w r2, {r2, r3}
 
 	%0 = load i64** @b, align 4
 	%1 = load i64* %0, align 4