[ARM] Fix handling of thumb1 out-of-range frame offsets

LocalStackSlotPass assumes that isFrameOffsetLegal doesn't change its
answer when the base register changes. Unfortunately this isn't true
in thumb1, where SP-based loads allow a larger offset than
non-SP-based loads, and this causes the base register reuse code to
generate instructions that are unencodable, causing an assertion
failure. 

Solve this by adding a BaseReg parameter to isFrameOffsetLegal, which
ARMBaseRegisterInfo can then make use of to give the correct answer. 

Differential Revision: http://reviews.llvm.org/D8419

llvm-svn: 232825

2 files changed, 3 insertions, 2 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCRegisterInfo.cpp b/llvm/lib/Target/PowerPC/PPCRegisterInfo.cpp
index b0c3d60ef08..8653734c8c6 100644
--- a/llvm/lib/Target/PowerPC/PPCRegisterInfo.cpp
+++ b/llvm/lib/Target/PowerPC/PPCRegisterInfo.cpp
@@ -993,7 +993,7 @@ needsFrameBaseReg(MachineInstr *MI, int64_t Offset) const {
 
   // The frame pointer will point to the end of the stack, so estimate the
   // offset as the difference between the object offset and the FP location.
-  return !isFrameOffsetLegal(MI, Offset);
+  return !isFrameOffsetLegal(MI, getBaseRegister(MF), Offset);
 }
 
 /// Insert defining instruction(s) for BaseReg to
@@ -1045,6 +1045,7 @@ void PPCRegisterInfo::resolveFrameIndex(MachineInstr &MI, unsigned BaseReg,
 }
 
 bool PPCRegisterInfo::isFrameOffsetLegal(const MachineInstr *MI,
+                                         unsigned BaseReg,
                                          int64_t Offset) const {
   unsigned FIOperandNum = 0;
   while (!MI->getOperand(FIOperandNum).isFI()) {
diff --git a/llvm/lib/Target/PowerPC/PPCRegisterInfo.h b/llvm/lib/Target/PowerPC/PPCRegisterInfo.h
index 03421745e6f..765d5745628 100644
--- a/llvm/lib/Target/PowerPC/PPCRegisterInfo.h
+++ b/llvm/lib/Target/PowerPC/PPCRegisterInfo.h
@@ -94,7 +94,7 @@ public:
                                     int64_t Offset) const override;
   void resolveFrameIndex(MachineInstr &MI, unsigned BaseReg,
                          int64_t Offset) const override;
-  bool isFrameOffsetLegal(const MachineInstr *MI,
+  bool isFrameOffsetLegal(const MachineInstr *MI, unsigned BaseReg,
                           int64_t Offset) const override;
 
   // Debug information queries.