[PATCH] D97672: [DeadArgElim] Do not optimize builtin annotated calls.

[Jeroen Dobbelaere via Phabricator via llvm-commits]

jeroen.dobbelaere created this revision.
jeroen.dobbelaere added reviewers: fhahn, probinson, jdoerfert, rsmith.
Herald added a subscriber: hiraditya.
jeroen.dobbelaere requested review of this revision.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

Do not optimize builtin annotated calls, based on the visibility on a
 possible implementation. Other optimization passes might still need the
 operand.

This fixes https://bugs.llvm.org/show_bug.cgi?id=49022


https://reviews.llvm.org/D97672

Files:
  llvm/lib/Transforms/IPO/DeadArgumentElimination.cpp
  llvm/test/Transforms/DeadArgElim/builtin_functions.ll


Index: llvm/test/Transforms/DeadArgElim/builtin_functions.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/DeadArgElim/builtin_functions.ll
@@ -0,0 +1,36 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --function-signature
+; RUN: opt -S -deadargelim %s | FileCheck %s
+
+; Function Attrs: nobuiltin nounwind uwtable mustprogress
+define dso_local void @_ZdlPv(i8* %0) #0 {
+; CHECK-LABEL: define {{[^@]+}}@_ZdlPv
+; CHECK-SAME: (i8* [[TMP0:%.*]]) [[ATTR0:#.*]] {
+; CHECK-NEXT:    ret void
+;
+  ret void
+}
+
+; The arguments for builtin annotated call must not be replaced
+define void @use_builtin_delete(i8* %p) {
+; CHECK-LABEL: define {{[^@]+}}@use_builtin_delete
+; CHECK-SAME: (i8* [[P:%.*]]) {
+; CHECK-NEXT:    call void @_ZdlPv(i8* [[P]]) [[ATTR1:#.*]]
+; CHECK-NEXT:    ret void
+;
+  call void @_ZdlPv(i8* %p) #1
+  ret void
+}
+
+define void @use_other_delete(i8* %p) {
+; CHECK-LABEL: define {{[^@]+}}@use_other_delete
+; CHECK-SAME: (i8* [[P:%.*]]) {
+; CHECK-NEXT:    call void @_ZdlPv(i8* undef) [[ATTR2:#.*]]
+; CHECK-NEXT:    ret void
+;
+  call void @_ZdlPv(i8* %p) #2
+  ret void
+}
+
+attributes #0 = { nobuiltin nounwind uwtable mustprogress readnone willreturn }
+attributes #1 = { builtin nounwind }
+attributes #2 = { nounwind }
Index: llvm/lib/Transforms/IPO/DeadArgumentElimination.cpp
===================================================================
--- llvm/lib/Transforms/IPO/DeadArgumentElimination.cpp
+++ llvm/lib/Transforms/IPO/DeadArgumentElimination.cpp
@@ -306,6 +306,12 @@
     if (!CB || !CB->isCallee(&U))
       continue;
 
+    // Don't touch builtin annotated calls. The analysis might have seen a
+    // (nobuiltin) implementation that allows to optimize an argument, but other
+    // optimizations of builtin calls might still depend on that argument.
+    if (CB->hasFnAttr(Attribute::Builtin))
+      continue;
+
     // Now go through all unused args and replace them with "undef".
     for (unsigned I = 0, E = UnusedArgs.size(); I != E; ++I) {
       unsigned ArgNo = UnusedArgs[I];


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D97672.327066.patch
Type: text/x-patch
Size: 2142 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20210301/f4826c27/attachment.bin>