[llvm] b26c417 - [InlineCost] Drop Requirements around ByVal Arguments

[via llvm-commits]

Author: Aiden Grossman
Date: 2026-07-14T06:14:04-07:00
New Revision: b26c417dd887aec06f4a09cd23a979b705c59fa2

URL: https://github.com/llvm/llvm-project/commit/b26c417dd887aec06f4a09cd23a979b705c59fa2
DIFF: https://github.com/llvm/llvm-project/commit/b26c417dd887aec06f4a09cd23a979b705c59fa2.diff

LOG: [InlineCost] Drop Requirements around ByVal Arguments

The underlying behavior was fixed in
e47359a925b88cd081ea85d10b55b0625d17b212, but given that the example
was marked alwaysinline, it bypassed any legality checks it would have
otherwise hit.

See
https://github.com/llvm/llvm-project/pull/97306#discussion_r1679306183
for discussion around which address space we should be using/legality.

This is necessary to preserve the behavior in
byval-with-non-alloca-addrspace.ll after we enable function attribute
compatibility checks in always-inline.

Reviewers: aeubanks, nikic, arsenm

Pull Request: https://github.com/llvm/llvm-project/pull/209344

Added: 
    

Modified: 
    llvm/lib/Analysis/InlineCost.cpp
    llvm/test/Transforms/Inline/byval.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/InlineCost.cpp b/llvm/lib/Analysis/InlineCost.cpp
index c3823931a7bcb..73f7f5e6cba04 100644
--- a/llvm/lib/Analysis/InlineCost.cpp
+++ b/llvm/lib/Analysis/InlineCost.cpp
@@ -3197,20 +3197,6 @@ std::optional<InlineResult> llvm::getAttributeBasedInliningDecision(
   if (Callee->isPresplitCoroutine())
     return InlineResult::failure("unsplited coroutine call");
 
-  // Never inline calls with byval arguments that does not have the alloca
-  // address space. Since byval arguments can be replaced with a copy to an
-  // alloca, the inlined code would need to be adjusted to handle that the
-  // argument is in the alloca address space (so it is a little bit complicated
-  // to solve).
-  unsigned AllocaAS = Callee->getDataLayout().getAllocaAddrSpace();
-  for (unsigned I = 0, E = Call.arg_size(); I != E; ++I)
-    if (Call.isByValArgument(I)) {
-      PointerType *PTy = cast<PointerType>(Call.getArgOperand(I)->getType());
-      if (PTy->getAddressSpace() != AllocaAS)
-        return InlineResult::failure("byval arguments without alloca"
-                                     " address space");
-    }
-
   // Inlining into a function with less target features is unsound, so enforce
   // this even if alwaysinline is used.
   Function *Caller = Call.getCaller();

diff  --git a/llvm/test/Transforms/Inline/byval.ll b/llvm/test/Transforms/Inline/byval.ll
index d435ddfa73fd0..2640b1e84397f 100644
--- a/llvm/test/Transforms/Inline/byval.ll
+++ b/llvm/test/Transforms/Inline/byval.ll
@@ -182,14 +182,6 @@ entry:
 @c = common addrspace(1) global i32 0, align 4
 
 define internal void @f5_as1(ptr addrspace(1) byval(%struct.S1) nocapture readonly align 4 %p) {
-; CHECK-LABEL: define internal void @f5_as1(
-; CHECK-SAME: ptr addrspace(1) readonly byval([[STRUCT_S1:%.*]]) align 4 captures(none) [[P:%.*]]) {
-; CHECK-NEXT:  entry:
-; CHECK-NEXT:    store i32 0, ptr addrspace(1) @d, align 4
-; CHECK-NEXT:    [[TMP0:%.*]] = load i32, ptr addrspace(1) [[P]], align 4
-; CHECK-NEXT:    store i32 [[TMP0]], ptr addrspace(1) @c, align 4
-; CHECK-NEXT:    ret void
-;
 entry:
   store i32 0, ptr addrspace(1) @d, align 4
   %0 = load i32, ptr addrspace(1) %p, align 4
@@ -200,7 +192,13 @@ entry:
 define i32 @test5_as1() {
 ; CHECK-LABEL: define i32 @test5_as1() {
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    tail call void @f5_as1(ptr addrspace(1) byval([[STRUCT_S1:%.*]]) align 4 @d)
+; CHECK-NEXT:    [[D:%.*]] = alloca [[STRUCT_S1:%.*]], align 8, addrspace(1)
+; CHECK-NEXT:    call void @llvm.lifetime.start.p1(ptr addrspace(1) [[D]])
+; CHECK-NEXT:    call void @llvm.memcpy.p1.p1.i64(ptr addrspace(1) align 8 [[D]], ptr addrspace(1) align 4 @d, i64 4, i1 false)
+; CHECK-NEXT:    store i32 0, ptr addrspace(1) @d, align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = load i32, ptr addrspace(1) [[D]], align 4
+; CHECK-NEXT:    store i32 [[TMP1]], ptr addrspace(1) @c, align 4
+; CHECK-NEXT:    call void @llvm.lifetime.end.p1(ptr addrspace(1) [[D]])
 ; CHECK-NEXT:    [[TMP0:%.*]] = load i32, ptr addrspace(1) @c, align 4
 ; CHECK-NEXT:    ret i32 [[TMP0]]
 ;