[llvm] 1e392fc - [ArgPromotion] Replace all md uses of promoted values with undef.

[Florian Hahn via llvm-commits]

Author: Florian Hahn
Date: 2020-08-03T19:31:53+01:00
New Revision: 1e392fc44584a4909b4dced02b8386b48963002b

URL: https://github.com/llvm/llvm-project/commit/1e392fc44584a4909b4dced02b8386b48963002b
DIFF: https://github.com/llvm/llvm-project/commit/1e392fc44584a4909b4dced02b8386b48963002b.diff

LOG: [ArgPromotion] Replace all md uses of promoted values with undef.

Currently, ArgPromotion may leave metadata uses of promoted values,
which will end up in the wrong function, creating invalid IR.

PR33641 fixed this for dead arguments, but it can be also be triggered
arguments with users that are promoted (see the updated test case).

We also have to drop uses to them after promoting them. We need to do
this after dealing with the non-metadata uses, so I also moved the empty
use case to the loop that deals with updating the arguments of the new
function.

Reviewed By: aprantl

Differential Revision: https://reviews.llvm.org/D85127

Added: 
    

Modified: 
    llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
    llvm/test/Transforms/ArgumentPromotion/pr33641_remove_arg_dbgvalue.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp b/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
index ad0d7eb51507..d511ad2729ab 100644
--- a/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
+++ b/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
@@ -33,6 +33,7 @@
 #include "llvm/ADT/None.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/ScopeExit.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
@@ -153,10 +154,6 @@ doPromotion(Function *F, SmallPtrSetImpl<Argument *> &ArgsToPromote,
     } else if (I->use_empty()) {
       // Dead argument (which are always marked as promotable)
       ++NumArgumentsDead;
-
-      // There may be remaining metadata uses of the argument for things like
-      // llvm.dbg.value. Replace them with undef.
-      I->replaceAllUsesWith(UndefValue::get(I->getType()));
     } else {
       // Okay, this is being promoted. This means that the only uses are loads
       // or GEPs which are only used by loads
@@ -414,6 +411,11 @@ doPromotion(Function *F, SmallPtrSetImpl<Argument *> &ArgsToPromote,
       continue;
     }
 
+    // There potentially are metadata uses for things like llvm.dbg.value.
+    // Replace them with undef, after handling the other regular uses.
+    auto RauwUndefMetadata = make_scope_exit(
+        [&]() { I->replaceAllUsesWith(UndefValue::get(I->getType())); });
+
     if (I->use_empty())
       continue;
 
@@ -465,7 +467,6 @@ doPromotion(Function *F, SmallPtrSetImpl<Argument *> &ArgsToPromote,
         GEP->eraseFromParent();
       }
     }
-
     // Increment I2 past all of the arguments added for this promoted pointer.
     std::advance(I2, ArgIndices.size());
   }

diff  --git a/llvm/test/Transforms/ArgumentPromotion/pr33641_remove_arg_dbgvalue.ll b/llvm/test/Transforms/ArgumentPromotion/pr33641_remove_arg_dbgvalue.ll
index 4c2503d8b0cc..8dcc5b8c4f13 100644
--- a/llvm/test/Transforms/ArgumentPromotion/pr33641_remove_arg_dbgvalue.ll
+++ b/llvm/test/Transforms/ArgumentPromotion/pr33641_remove_arg_dbgvalue.ll
@@ -30,6 +30,52 @@ define internal void @bar(%p_t %p)  {
 
 declare void @llvm.dbg.value(metadata, metadata, metadata)
 
+
+; Test case where the promoted argument has uses in @callee and we need to
+; retain a reference to the original function, because it is stored in @storer.
+define void @storer({i32, i32}* %ptr) {
+; CHECK-LABEL: define {{[^@]+}}@storer
+; CHECK-SAME: ({ i32, i32 }* [[PTR:%.*]])
+; CHECK-NEXT:    ret void
+;
+  %tmp = alloca i32 ({i32, i32}*)*
+  store i32 ({i32, i32}*)* @callee,  i32 ({i32, i32}*)** %tmp
+  ret void
+}
+
+define i32 @caller() {
+; CHECK-LABEL: define {{[^@]+}}@caller()
+; CHECK-NEXT:    [[TMP:%.*]] = alloca { i32, i32 }, align 8
+; CHECK-NEXT:    [[F_1:%.*]] = getelementptr { i32, i32 }, { i32, i32 }* [[TMP]], i32 0, i32 1
+; CHECK-NEXT:    store i32 10, i32* [[F_1]], align 4
+; CHECK-NEXT:    [[TMP_IDX:%.*]] = getelementptr { i32, i32 }, { i32, i32 }* [[TMP]], i64 0, i32 1
+; CHECK-NEXT:    [[TMP_IDX_VAL:%.*]] = load i32, i32* [[TMP_IDX]], align 4
+; CHECK-NEXT:    [[RES:%.*]] = call i32 @callee(i32 [[TMP_IDX_VAL]])
+; CHECK-NEXT:    ret i32 [[RES]]
+;
+  %tmp = alloca {i32, i32}
+  %f.1 = getelementptr {i32, i32}, {i32, i32}* %tmp, i32 0, i32 1
+  store i32 10, i32* %f.1
+  %res = call i32 @callee({i32, i32}* %tmp)
+  ret i32 %res
+}
+
+define internal i32 @callee({i32, i32}* %ptr)  !dbg !7 {
+; CHECK-LABEL: define {{[^@]+}}@callee
+; CHECK-SAME: (i32 [[PTR_0_1_VAL:%.*]]) !dbg !6
+; CHECK-NEXT:    call void @llvm.dbg.value(metadata { i32, i32 }* undef, metadata !7, metadata !DIExpression()), !dbg !8
+; CHECK-NEXT:    call void @llvm.dbg.value(metadata i32 [[PTR_0_1_VAL]], metadata !7, metadata !DIExpression()), !dbg !8
+; CHECK-NEXT:    ret i32 [[PTR_0_1_VAL]]
+;
+  call void @llvm.dbg.value(metadata {i32, i32}* %ptr, metadata !8, metadata !9), !dbg !10
+  %f.1 = getelementptr {i32, i32}, {i32, i32}* %ptr, i32 0, i32 1
+  %l.1 = load i32, i32* %f.1
+  call void @llvm.dbg.value(metadata i32 %l.1, metadata !8, metadata !9), !dbg !10
+  ret i32 %l.1
+}
+
+
+
 !llvm.dbg.cu = !{!0}
 !llvm.module.flags = !{!2}
 
@@ -40,3 +86,7 @@ declare void @llvm.dbg.value(metadata, metadata, metadata)
 !4 = !DILocalVariable(name: "p", scope: !3)
 !5 = !DIExpression()
 !6 = !DILocation(line: 1, column: 1, scope: !3)
+!7 = distinct !DISubprogram(name: "callee", unit: !0)
+!8 = !DILocalVariable(name: "c", scope: !7)
+!9 = !DIExpression()
+!10 = !DILocation(line: 2, column: 2, scope: !7)