[llvm] fb470db - [AArch64] Avoid inlining if ZT0 needs preserving. (#101343)

[via llvm-commits]

Author: Sander de Smalen
Date: 2024-08-02T10:29:08+01:00
New Revision: fb470db7b3a8ce6853e8bf17d235617a2fa79434

URL: https://github.com/llvm/llvm-project/commit/fb470db7b3a8ce6853e8bf17d235617a2fa79434
DIFF: https://github.com/llvm/llvm-project/commit/fb470db7b3a8ce6853e8bf17d235617a2fa79434.diff

LOG: [AArch64] Avoid inlining if ZT0 needs preserving. (#101343)

Inlining may result in different behaviour when the callee clobbers ZT0,
because normally the call-site will have code to preserve ZT0. When
inlining the function this code to preserve ZT0 will no longer be
emitted, and so the resulting behaviour of the program is changed.

Added: 
    

Modified: 
    llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
    llvm/test/Transforms/Inline/AArch64/sme-pstateza-attrs.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
index 79c0e45e3aa5b..b8f19fa87e2ab 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
@@ -254,7 +254,8 @@ bool AArch64TTIImpl::areInlineCompatible(const Function *Caller,
     return false;
 
   if (CallerAttrs.requiresLazySave(CalleeAttrs) ||
-      CallerAttrs.requiresSMChange(CalleeAttrs)) {
+      CallerAttrs.requiresSMChange(CalleeAttrs) ||
+      CallerAttrs.requiresPreservingZT0(CalleeAttrs)) {
     if (hasPossibleIncompatibleOps(Callee))
       return false;
   }

diff  --git a/llvm/test/Transforms/Inline/AArch64/sme-pstateza-attrs.ll b/llvm/test/Transforms/Inline/AArch64/sme-pstateza-attrs.ll
index 816492768cc0f..5e638103a2b06 100644
--- a/llvm/test/Transforms/Inline/AArch64/sme-pstateza-attrs.ll
+++ b/llvm/test/Transforms/Inline/AArch64/sme-pstateza-attrs.ll
@@ -231,6 +231,51 @@ define void @shared_za_caller_private_za_callee_call_tpidr2_restore_dont_inline(
   ret void
 }
 
+define void @nonzt0_callee() {
+; CHECK-LABEL: define void @nonzt0_callee
+; CHECK-SAME: () #[[ATTR0]] {
+; CHECK-NEXT:    call void asm sideeffect "
+; CHECK-NEXT:    call void @inlined_body()
+; CHECK-NEXT:    ret void
+;
+  call void asm sideeffect "; inlineasm", ""()
+  call void @inlined_body()
+  ret void
+}
+
+define void @shared_zt0_caller_nonzt0_callee_dont_inline() "aarch64_inout_zt0" {
+; CHECK-LABEL: define void @shared_zt0_caller_nonzt0_callee_dont_inline
+; CHECK-SAME: () #[[ATTR3:[0-9]+]] {
+; CHECK-NEXT:    call void @nonzt0_callee()
+; CHECK-NEXT:    ret void
+;
+  call void @nonzt0_callee()
+  ret void
+}
+
+define void @shared_zt0_callee() "aarch64_inout_zt0" {
+; CHECK-LABEL: define void @shared_zt0_callee
+; CHECK-SAME: () #[[ATTR3]] {
+; CHECK-NEXT:    call void asm sideeffect "
+; CHECK-NEXT:    call void @inlined_body()
+; CHECK-NEXT:    ret void
+;
+  call void asm sideeffect "; inlineasm", ""()
+  call void @inlined_body()
+  ret void
+}
+
+define void @shared_zt0_caller_shared_zt0_callee_inline() "aarch64_inout_zt0" {
+; CHECK-LABEL: define void @shared_zt0_caller_shared_zt0_callee_inline
+; CHECK-SAME: () #[[ATTR3]] {
+; CHECK-NEXT:    call void asm sideeffect "
+; CHECK-NEXT:    call void @inlined_body()
+; CHECK-NEXT:    ret void
+;
+  call void @shared_zt0_callee()
+  ret void
+}
+
 declare void @__arm_za_disable()
 declare void @__arm_tpidr2_save()
 declare void @__arm_tpidr2_restore(ptr)