qcolombet updated this revision to Diff 426555.
qcolombet added a comment.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
- includes fixes to clang tests that were missed in the original commit.
If someone knows who we can add from the clang side to double check the tests
update that would be great!
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D124699/new/
https://reviews.llvm.org/D124699
Files:
clang/test/CodeGen/debug-info-block-vars.c
clang/test/CodeGenObjCXX/nrvo.mm
llvm/lib/Transforms/IPO/DeadArgumentElimination.cpp
llvm/test/Transforms/DeadArgElim/fct_ptr.ll
Index: llvm/test/Transforms/DeadArgElim/fct_ptr.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/DeadArgElim/fct_ptr.ll
@@ -0,0 +1,67 @@
+; RUN: opt -S %s -deadargelim -o - | FileCheck %s
+; In that test @internal_fct is used by an instruction
+; we don't know how to rewrite (the comparison that produces
+; %cmp1).
+; Because of that use, we used to bail out on removing the
+; unused arguments for this function.
+; Yet, we should still be able to rewrite the direct calls that are
+; statically known, by replacing the related arguments with undef.
+; This is what we check on the call that produces %res2.
+
+define i32 @call_indirect(i32 (i32, i32, i32)* readnone %fct_ptr, i32 %arg1, i32 %arg2, i32 %arg3) {
+; CHECK-LABEL: @call_indirect(
+; CHECK-NEXT: [[CMP0:%.*]] = icmp eq i32 (i32, i32, i32)* [[FCT_PTR:%.*]], @external_fct
+; CHECK-NEXT: br i1 [[CMP0]], label [[CALL_EXT:%.*]], label [[CHK2:%.*]]
+; CHECK: call_ext:
+; CHECK-NEXT: [[RES1:%.*]] = tail call i32 @external_fct(i32 undef, i32 [[ARG2:%.*]], i32 undef)
+; CHECK-NEXT: br label [[END:%.*]]
+; CHECK: chk2:
+; CHECK-NEXT: [[CMP1:%.*]] = icmp eq i32 (i32, i32, i32)* [[FCT_PTR]], @internal_fct
+; CHECK-NEXT: br i1 [[CMP1]], label [[CALL_INT:%.*]], label [[CALL_OTHER:%.*]]
+; CHECK: call_int:
+; CHECK-NEXT: [[RES2:%.*]] = tail call i32 @internal_fct(i32 undef, i32 [[ARG2]], i32 undef)
+; CHECK-NEXT: br label [[END]]
+; CHECK: call_other:
+; CHECK-NEXT: [[RES3:%.*]] = tail call i32 @other_fct(i32 [[ARG2]])
+; CHECK-NEXT: br label [[END]]
+; CHECK: end:
+; CHECK-NEXT: [[FINAL_RES:%.*]] = phi i32 [ [[RES1]], [[CALL_EXT]] ], [ [[RES2]], [[CALL_INT]] ], [ [[RES3]], [[CALL_OTHER]] ]
+; CHECK-NEXT: ret i32 [[FINAL_RES]]
+;
+ %cmp0 = icmp eq i32 (i32, i32, i32)* %fct_ptr, @external_fct
+ br i1 %cmp0, label %call_ext, label %chk2
+
+call_ext:
+ %res1 = tail call i32 @external_fct(i32 %arg1, i32 %arg2, i32 %arg3)
+ br label %end
+
+chk2:
+ %cmp1 = icmp eq i32 (i32, i32, i32)* %fct_ptr, @internal_fct
+ br i1 %cmp1, label %call_int, label %call_other
+
+call_int:
+ %res2 = tail call i32 @internal_fct(i32 %arg1, i32 %arg2, i32 %arg3)
+ br label %end
+
+call_other:
+ %res3 = tail call i32 @other_fct(i32 %arg1, i32 %arg2, i32 %arg3)
+ br label %end
+
+end:
+ %final_res = phi i32 [%res1, %call_ext], [%res2, %call_int], [%res3, %call_other]
+ ret i32 %final_res
+}
+
+
+define i32 @external_fct(i32 %unused_arg1, i32 %arg2, i32 %unused_arg3) {
+ ret i32 %arg2
+}
+
+define internal i32 @internal_fct(i32 %unused_arg1, i32 %arg2, i32 %unused_arg3) {
+ ret i32 %arg2
+}
+
+define internal i32 @other_fct(i32 %unused_arg1, i32 %arg2, i32 %unused_arg3) {
+ ret i32 %arg2
+}
+
Index: llvm/lib/Transforms/IPO/DeadArgumentElimination.cpp
===================================================================
--- llvm/lib/Transforms/IPO/DeadArgumentElimination.cpp
+++ llvm/lib/Transforms/IPO/DeadArgumentElimination.cpp
@@ -268,9 +268,12 @@
if (!Fn.hasExactDefinition())
return false;
- // Functions with local linkage should already have been handled, except the
- // fragile (variadic) ones which we can improve here.
- if (Fn.hasLocalLinkage() && !Fn.getFunctionType()->isVarArg())
+ // Functions with local linkage should already have been handled, except if
+ // they are fully alive (e.g., called indirectly) and except for the fragile
+ // (variadic) ones. In these cases, we may still be able to improve their
+ // statically known call sites.
+ if ((Fn.hasLocalLinkage() && !LiveFunctions.count(&Fn)) &&
+ !Fn.getFunctionType()->isVarArg())
return false;
// Don't touch naked functions. The assembly might be using an argument, or
Index: clang/test/CodeGenObjCXX/nrvo.mm
===================================================================
--- clang/test/CodeGenObjCXX/nrvo.mm
+++ clang/test/CodeGenObjCXX/nrvo.mm
@@ -22,7 +22,11 @@
X blocksNRVO() {
return ^{
- // CHECK-LABEL: define internal void @___Z10blocksNRVOv_block_invoke
+ // With the optimizer enabled, the DeadArgElim pass is able to
+ // mark the block litteral address argument as unused and later the
+ // related block_litteral global variable is removed.
+ // This allows to promote this call to a fastcc call.
+ // CHECK-LABEL: define internal fastcc void @___Z10blocksNRVOv_block_invoke
X x;
// CHECK: call void @_ZN1XC1Ev
// CHECK-NEXT: ret void
Index: clang/test/CodeGen/debug-info-block-vars.c
===================================================================
--- clang/test/CodeGen/debug-info-block-vars.c
+++ clang/test/CodeGen/debug-info-block-vars.c
@@ -11,7 +11,10 @@
// CHECK: call void @llvm.dbg.declare(metadata i8** %.block_descriptor.addr,
// CHECK-SAME: metadata !DIExpression())
// CHECK-OPT-NOT: alloca
-// CHECK-OPT: call void @llvm.dbg.value(metadata i8* %.block_descriptor,
+// Since the block address is not used anywhere in this function,
+// the optimizer (DeadArgElim) has replaced all the false uses
+// (i.e., metadata users) with undef.
+// CHECK-OPT: call void @llvm.dbg.value(metadata i8* undef,
// CHECK-OPT-SAME: metadata !DIExpression())
void f(void) {
a(^{
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