Improve handling of stack accesses in Thumb-1

Thumb-1 only allows SP-based LDR and STR to be word-sized, and SP-base LDR,
STR, and ADD only allow offsets that are a multiple of 4. Make some changes
to better make use of these instructions:

* Use word loads for anyext byte and halfword loads from the stack.
* Enforce 4-byte alignment on objects accessed in this way, to ensure that
  the offset is valid.
* Do the same for objects whose frame index is used, in order to avoid having
  to use more than one ADD to generate the frame index.
* Correct how many bits of offset we think AddrModeT1_s has.

Patch by John Brawn.

llvm-svn: 230496

1 files changed, 6 insertions, 8 deletions

diff --git a/llvm/test/CodeGen/ARM/debug-frame-vararg.ll b/llvm/test/CodeGen/ARM/debug-frame-vararg.ll
index 05521d80646..65be2db6923 100644
--- a/llvm/test/CodeGen/ARM/debug-frame-vararg.ll
+++ b/llvm/test/CodeGen/ARM/debug-frame-vararg.ll
@@ -88,24 +88,22 @@
 ; CHECK-THUMB-FP: .cfi_startproc
 ; CHECK-THUMB-FP: sub    sp, #16
 ; CHECK-THUMB-FP: .cfi_def_cfa_offset 16
-; CHECK-THUMB-FP: push   {r4, r5, r7, lr}
-; CHECK-THUMB-FP: .cfi_def_cfa_offset 32
+; CHECK-THUMB-FP: push   {r4, lr}
+; CHECK-THUMB-FP: .cfi_def_cfa_offset 24
 ; CHECK-THUMB-FP: .cfi_offset lr, -20
-; CHECK-THUMB-FP: .cfi_offset r7, -24
-; CHECK-THUMB-FP: .cfi_offset r5, -28
-; CHECK-THUMB-FP: .cfi_offset r4, -32
+; CHECK-THUMB-FP: .cfi_offset r4, -24
 ; CHECK-THUMB-FP: sub    sp, #8
-; CHECK-THUMB-FP: .cfi_def_cfa_offset 40
+; CHECK-THUMB-FP: .cfi_def_cfa_offset 32
 
 ; CHECK-THUMB-FP-ELIM-LABEL: sum
 ; CHECK-THUMB-FP-ELIM: .cfi_startproc
 ; CHECK-THUMB-FP-ELIM: sub    sp, #16
 ; CHECK-THUMB-FP-ELIM: .cfi_def_cfa_offset 16
-; CHECK-THUMB-FP-ELIM: push   {r4, r5, r7, lr}
+; CHECK-THUMB-FP-ELIM: push   {r4, r6, r7, lr}
 ; CHECK-THUMB-FP-ELIM: .cfi_def_cfa_offset 32
 ; CHECK-THUMB-FP-ELIM: .cfi_offset lr, -20
 ; CHECK-THUMB-FP-ELIM: .cfi_offset r7, -24
-; CHECK-THUMB-FP-ELIM: .cfi_offset r5, -28
+; CHECK-THUMB-FP-ELIM: .cfi_offset r6, -28
 ; CHECK-THUMB-FP-ELIM: .cfi_offset r4, -32
 ; CHECK-THUMB-FP-ELIM: add    r7, sp, #8
 ; CHECK-THUMB-FP-ELIM: .cfi_def_cfa r7, 24