ARMLoadStoreOpt: Merge subs/adds into LDRD/STRD; Factor out common code

Re-apply of r241928 which had to be reverted because of the r241926
revert.

This commit factors out common code from MergeBaseUpdateLoadStore() and
MergeBaseUpdateLSMultiple() and introduces a new function
MergeBaseUpdateLSDouble() which merges adds/subs preceding/following a
strd/ldrd instruction into an strd/ldrd instruction with writeback where
possible.

Differential Revision: http://reviews.llvm.org/D10676

llvm-svn: 242743

1 files changed, 52 insertions, 4 deletions

diff --git a/llvm/test/CodeGen/ARM/ldrd.ll b/llvm/test/CodeGen/ARM/ldrd.ll
index 5411618ed86..56cdcaedf90 100644
--- a/llvm/test/CodeGen/ARM/ldrd.ll
+++ b/llvm/test/CodeGen/ARM/ldrd.ll
@@ -112,10 +112,10 @@ entry:
 }
 
 ; CHECK-LABEL: strd_spill_ldrd_reload:
-; A8: strd r1, r0, [sp]
-; M3: strd r1, r0, [sp]
-; BASIC: strd r1, r0, [sp]
-; GREEDY: strd r0, r1, [sp]
+; A8: strd r1, r0, [sp, #-8]!
+; M3: strd r1, r0, [sp, #-8]!
+; BASIC: strd r1, r0, [sp, #-8]!
+; GREEDY: strd r0, r1, [sp, #-8]!
 ; CHECK: @ InlineAsm Start
 ; CHECK: @ InlineAsm End
 ; A8: ldrd r2, r1, [sp]
@@ -131,5 +131,53 @@ define void @strd_spill_ldrd_reload(i32 %v0, i32 %v1) {
   ret void
 }
 
+declare void @extfunc2(i32*, i32, i32)
+
+; CHECK-LABEL: ldrd_postupdate_dec:
+; CHECK: ldrd r1, r2, [r0], #-8
+; CHECK-NEXT: bl{{x?}} _extfunc
+define void @ldrd_postupdate_dec(i32* %p0) {
+  %p0.1 = getelementptr i32, i32* %p0, i32 1
+  %v0 = load i32, i32* %p0
+  %v1 = load i32, i32* %p0.1
+  %p1 = getelementptr i32, i32* %p0, i32 -2
+  call void @extfunc2(i32* %p1, i32 %v0, i32 %v1)
+  ret void
+}
+
+; CHECK-LABEL: ldrd_postupdate_inc:
+; CHECK: ldrd r1, r2, [r0], #8
+; CHECK-NEXT: bl{{x?}} _extfunc
+define void @ldrd_postupdate_inc(i32* %p0) {
+  %p0.1 = getelementptr i32, i32* %p0, i32 1
+  %v0 = load i32, i32* %p0
+  %v1 = load i32, i32* %p0.1
+  %p1 = getelementptr i32, i32* %p0, i32 2
+  call void @extfunc2(i32* %p1, i32 %v0, i32 %v1)
+  ret void
+}
+
+; CHECK-LABEL: strd_postupdate_dec:
+; CHECK: strd r1, r2, [r0], #-8
+; CHECK-NEXT: bx lr
+define i32* @strd_postupdate_dec(i32* %p0, i32 %v0, i32 %v1) {
+  %p0.1 = getelementptr i32, i32* %p0, i32 1
+  store i32 %v0, i32* %p0
+  store i32 %v1, i32* %p0.1
+  %p1 = getelementptr i32, i32* %p0, i32 -2
+  ret i32* %p1
+}
+
+; CHECK-LABEL: strd_postupdate_inc:
+; CHECK: strd r1, r2, [r0], #8
+; CHECK-NEXT: bx lr
+define i32* @strd_postupdate_inc(i32* %p0, i32 %v0, i32 %v1) {
+  %p0.1 = getelementptr i32, i32* %p0, i32 1
+  store i32 %v0, i32* %p0
+  store i32 %v1, i32* %p0.1
+  %p1 = getelementptr i32, i32* %p0, i32 2
+  ret i32* %p1
+}
+
 declare void @llvm.lifetime.start(i64, i8* nocapture) nounwind
 declare void @llvm.lifetime.end(i64, i8* nocapture) nounwind