[Thumb] Emit Thumb move in both Thumb modes for struct_byval predicates

Summary:
The MOV/MOVT instructions being chosen for struct_byval predicates was
conditional only on Thumb2, resulting in an ARM MOV/MOVT instruction
being incorrectly emitted in Thumb1 mode. This is especially apparent
with v8-m.base targets. This patch ensures that Thumb instructions are
emitted in both Thumb modes.

Reviewers: rengolin, t.p.northover

Subscribers: llvm-commits, aemerson, rengolin

Differential Revision: https://reviews.llvm.org/D22865

llvm-svn: 277128

2 files changed, 34 insertions, 4 deletions

diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index 82c32af3b86..2571e8b9368 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -7904,6 +7904,7 @@ ARMTargetLowering::EmitStructByval(MachineInstr &MI,
 
   bool IsThumb1 = Subtarget->isThumb1Only();
   bool IsThumb2 = Subtarget->isThumb2();
+  bool IsThumb = Subtarget->isThumb();
 
   if (Align & 1) {
     UnitSize = 1;
@@ -7925,7 +7926,7 @@ ARMTargetLowering::EmitStructByval(MachineInstr &MI,
 
   // Select the correct opcode and register class for unit size load/store
   bool IsNeon = UnitSize >= 8;
-  TRC = (IsThumb1 || IsThumb2) ? &ARM::tGPRRegClass : &ARM::GPRRegClass;
+  TRC = IsThumb ? &ARM::tGPRRegClass : &ARM::GPRRegClass;
   if (IsNeon)
     VecTRC = UnitSize == 16 ? &ARM::DPairRegClass
                             : UnitSize == 8 ? &ARM::DPRRegClass
@@ -8007,12 +8008,12 @@ ARMTargetLowering::EmitStructByval(MachineInstr &MI,
     if ((LoopSize & 0xFFFF0000) != 0)
       Vtmp = MRI.createVirtualRegister(TRC);
     AddDefaultPred(BuildMI(BB, dl,
-                           TII->get(IsThumb2 ? ARM::t2MOVi16 : ARM::MOVi16),
+                           TII->get(IsThumb ? ARM::t2MOVi16 : ARM::MOVi16),
                            Vtmp).addImm(LoopSize & 0xFFFF));
 
     if ((LoopSize & 0xFFFF0000) != 0)
       AddDefaultPred(BuildMI(BB, dl,
-                             TII->get(IsThumb2 ? ARM::t2MOVTi16 : ARM::MOVTi16),
+                             TII->get(IsThumb ? ARM::t2MOVTi16 : ARM::MOVTi16),
                              varEnd)
                          .addReg(Vtmp)
                          .addImm(LoopSize >> 16));
@@ -8027,7 +8028,7 @@ ARMTargetLowering::EmitStructByval(MachineInstr &MI,
       Align = MF->getDataLayout().getTypeAllocSize(C->getType());
     unsigned Idx = ConstantPool->getConstantPoolIndex(C, Align);
 
-    if (IsThumb1)
+    if (IsThumb)
       AddDefaultPred(BuildMI(*BB, MI, dl, TII->get(ARM::tLDRpci)).addReg(
           varEnd, RegState::Define).addConstantPoolIndex(Idx));
     else
diff --git a/llvm/test/CodeGen/ARM/struct_byval_arm_t1_t2.ll b/llvm/test/CodeGen/ARM/struct_byval_arm_t1_t2.ll
index 0a9bc3c87f9..fc4f11e8b45 100644
--- a/llvm/test/CodeGen/ARM/struct_byval_arm_t1_t2.ll
+++ b/llvm/test/CodeGen/ARM/struct_byval_arm_t1_t2.ll
@@ -7,6 +7,10 @@
 ;RUN: llc < %s -mtriple=thumbv5-none-linux-gnueabi              -verify-machineinstrs -filetype=obj | llvm-objdump -triple thumbv5-none-linux-gnueabi -disassemble - > %t
 ;RUN: cat %t | FileCheck %s --check-prefix=THUMB1
 ;RUN: cat %t | FileCheck %s --check-prefix=T1POST
+;RUN: llc < %s -mtriple=thumbv8m.base-arm-none-eabi             -verify-machineinstrs -filetype=obj | llvm-objdump -triple thumbv8m.base-arm-none-eabi -disassemble - > %t
+;RUN: cat %t | FileCheck %s --check-prefix=THUMB1
+;RUN: cat %t | FileCheck %s --check-prefix=T1POST
+;RUN: cat %t | FileCheck %s --check-prefix=V8MBASE
 
 ;This file contains auto generated tests for the lowering of passing structs
 ;byval in the arm backend. We have tests for both packed and unpacked
@@ -44,6 +48,10 @@ declare void @use_J(%struct.J* byval)
 declare void @use_K(%struct.K* byval)
 %struct.L = type  { [ 100 x i32 ], [ 3 x i8 ] }  ; 403 bytes
 declare void @use_L(%struct.L* byval)
+%struct.M = type  { [  64 x i8 ] }   ; 64 bytes
+declare void @use_M(%struct.M* byval)
+%struct.N = type  { [ 128 x i8 ] }  ; 128 bytes
+declare void @use_N(%struct.N* byval)
 
 ;ARM-LABEL:    test_A_1:
 ;THUMB2-LABEL: test_A_1:
@@ -1521,3 +1529,24 @@ declare void @use_L(%struct.L* byval)
     call void @use_L(%struct.L* byval align 16 %a)
     ret void
   }
+;V8MBASE-LABEL: test_M:
+  define void @test_M() {
+
+;V8MBASE:      ldrb    r{{[0-9]+}}, {{\[}}[[BASE:r[0-9]+]]{{\]}}
+;V8MBASE:      adds    [[BASE]], #1
+;V8MBASE-NOT:  movw
+  entry:
+    %a = alloca %struct.M, align 1
+    call void @use_M(%struct.M* byval align 1 %a)
+    ret void
+  }
+;V8MBASE-LABEL: test_N:
+  define void @test_N() {
+
+;V8MBASE:      movw    r{{[0-9]+}}, #{{[0-9]+}}
+;V8MBASE-NOT:  b       #{{[0-9]+}}
+  entry:
+    %a = alloca %struct.N, align 1
+    call void @use_N(%struct.N* byval align 1 %a)
+    ret void
+  }