Backport [TailCallElim] Remove the readonly attribute of byval.

clang/docs/ReleaseNotes.rst

@@ -1103,12 +1103,6 @@ WebAssembly Support
 ^^^^^^^^^^^^^^^^^^^
 - The -mcpu=generic configuration now enables sign-ext and mutable-globals. These
   proposals are standardized and available in all major engines.
-- Shared library support (and PIC code generation) for WebAssembly is no longer
-  limited to the Emscripten target OS and now works with other targets such as
-  wasm32-wasi.  Note that the `format
-  <https://github.com/WebAssembly/tool-conventions/blob/main/DynamicLinking.md>`_
-  is not yet stable and may change between LLVM versions.  Also, WASI does not
-  yet have facilities to load dynamic libraries.
 
 DWARF Support in Clang
 ----------------------

clang/lib/Driver/ToolChains/WebAssembly.cpp

@@ -101,16 +101,13 @@ void wasm::Linker::ConstructJob(Compilation &C, const JobAction &JA,
           << CM << A->getOption().getName();
     }
   }
-  if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles, options::OPT_shared))
+  if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles))
     CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath(Crt1)));
   if (Entry) {
     CmdArgs.push_back(Args.MakeArgString("--entry"));
     CmdArgs.push_back(Args.MakeArgString(Entry));
   }
 
-  if (Args.hasArg(options::OPT_shared))
-    CmdArgs.push_back(Args.MakeArgString("-shared"));
-
   AddLinkerInputs(ToolChain, Inputs, Args, CmdArgs, JA);
 
   if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {

clang/test/Driver/wasm-toolchain.c

@@ -33,20 +33,6 @@
 // LINK_KNOWN: "-cc1" {{.*}} "-o" "[[temp:[^"]*]]"
 // LINK_KNOWN: wasm-ld{{.*}}" "-L/foo/lib/wasm32-wasi" "crt1.o" "[[temp]]" "-lc" "{{.*[/\\]}}libclang_rt.builtins-wasm32.a" "-o" "a.out"
 
-// -shared should be passed through to `wasm-ld` and not include crt1.o with a known OS.
-
-// RUN: %clang -### -shared --target=wasm32-wasi --sysroot=/foo %s 2>&1 \
-// RUN:   | FileCheck -check-prefix=LINK_KNOWN_SHARED %s
-// LINK_KNOWN_SHARED: "-cc1" {{.*}} "-o" "[[temp:[^"]*]]"
-// LINK_KNOWN_SHARED: wasm-ld{{.*}}" "-L/foo/lib/wasm32-wasi" "-shared" "[[temp]]" "-lc" "{{.*[/\\]}}libclang_rt.builtins-wasm32.a" "-o" "a.out"
-
-// -shared should be passed through to `wasm-ld` and not include crt1.o with an unknown OS.
-
-// RUN: %clang -### -shared --target=wasm32-unknown-unknown --sysroot=/foo %s 2>&1 \
-// RUN:   | FileCheck -check-prefix=LINK_UNKNOWN_SHARED %s
-// LINK_UNKNOWN_SHARED: "-cc1" {{.*}} "-o" "[[temp:[^"]*]]"
-// LINK_UNKNOWN_SHARED: wasm-ld{{.*}}" "-shared" "[[temp]]" "-lc" "{{.*[/\\]}}libclang_rt.builtins-wasm32.a" "-o" "a.out"
-
 // A basic C link command-line with optimization with known OS.
 
 // RUN: %clang -### -O2 --target=wasm32-wasi --sysroot=/foo %s 2>&1 \
@@ -60,18 +46,6 @@
 // RUN:   | FileCheck -check-prefix=COMPILE %s
 // COMPILE: "-cc1" {{.*}} "-internal-isystem" "/foo/include/wasm32-wasi" "-internal-isystem" "/foo/include"
 
-// -fPIC should work on a known OS
-
-// RUN: %clang -### -fPIC --target=wasm32-wasi --sysroot=/foo %s 2>&1 \
-// RUN:   | FileCheck -check-prefix=COMPILE_KNOWN_PIC %s
-// COMPILE_KNOWN_PIC: "-cc1" {{.*}} "-mrelocation-model" "pic" "-pic-level" "2" {{.*}} "-internal-isystem" "/foo/include/wasm32-wasi" "-internal-isystem" "/foo/include"
-
-// -fPIC should work on an unknown OS
-
-// RUN: %clang -### -fPIC --target=wasm32-unknown-unknown --sysroot=/foo %s 2>&1 \
-// RUN:   | FileCheck -check-prefix=COMPILE_UNKNOWN_PIC %s
-// COMPILE_UNKNOWN_PIC: "-cc1" {{.*}} "-mrelocation-model" "pic" "-pic-level" "2"
-
 // Thread-related command line tests.
 
 // '-pthread' sets +atomics, +bulk-memory, +mutable-globals, +sign-ext, and --shared-memory

llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp

@@ -98,6 +98,13 @@ static Reloc::Model getEffectiveRelocModel(std::optional<Reloc::Model> RM,
     return Reloc::Static;
   }
 
+  if (!TT.isOSEmscripten()) {
+    // Relocation modes other than static are currently implemented in a way
+    // that only works for Emscripten, so disable them if we aren't targeting
+    // Emscripten.
+    return Reloc::Static;
+  }
+
   return *RM;
 }
 

llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp

@@ -675,6 +675,12 @@ bool TailRecursionEliminator::eliminateCall(CallInst *CI) {
   for (unsigned I = 0, E = CI->arg_size(); I != E; ++I) {
     if (CI->isByValArgument(I)) {
       copyLocalTempOfByValueOperandIntoArguments(CI, I);
+      // When eliminating a tail call, we modify the values of the arguments.
+      // Therefore, if the byval parameter has a readonly attribute, we have to
+      // remove it. It is safe because, from the perspective of a caller, the
+      // byval parameter is always treated as "readonly," even if the readonly
+      // attribute is removed.
+      F.removeParamAttr(I, Attribute::ReadOnly);
       ArgumentPHIs[I]->addIncoming(F.getArg(I), BB);
     } else
       ArgumentPHIs[I]->addIncoming(CI->getArgOperand(I), BB);

llvm/test/Transforms/PhaseOrdering/pr64289-tce.ll

@@ -0,0 +1,27 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -O3 < %s | FileCheck %s
+
+; A miscompilation found on https://github.com/llvm/llvm-project/issues/64289.
+; 1. PostOrderFunctionAttrsPass added readonly to the parameter.
+; 2. TailCallElimPass modified the parameter but kept readonly.
+; 3. LICMPass incorrectly hoisted the load instruction.
+
+define void @pr64289(ptr noalias byval(i64) %x) {
+; CHECK-LABEL: @pr64289(
+; CHECK-NEXT:  start:
+; CHECK-NEXT:    ret void
+;
+start:
+  %new_x = alloca i64, align 8
+  %x_val = load i64, ptr %x, align 8
+  %is_zero = icmp eq i64 %x_val, 0
+  br i1 %is_zero, label %end, label %recurse
+
+recurse:
+  store i64 0, ptr %new_x, align 8
+  call void @pr64289(ptr %new_x)
+  br label %end
+
+end:
+  ret void
+}

llvm/test/Transforms/TailCallElim/tre-byval-parameter-2.ll

@@ -1,4 +1,4 @@
-; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --function-signature
 ; RUN: opt < %s -passes=tailcallelim -verify-dom-info -S | FileCheck %s
 
 ; the test was generated from the following C++ source:
@@ -24,23 +24,24 @@
 
 ; Function Attrs: noinline nounwind uwtable
 define dso_local void @_Z7dostuff1AS_i(ptr nocapture byval(%struct.A) align 8 %a, ptr nocapture readonly byval(%struct.A) align 8 %b, i32 %i) local_unnamed_addr #0 {
-; CHECK-LABEL: @_Z7dostuff1AS_i(
+; CHECK-LABEL: define {{[^@]+}}@_Z7dostuff1AS_i
+; CHECK-SAME: (ptr nocapture byval([[STRUCT_A:%.*]]) align 8 [[A:%.*]], ptr nocapture byval([[STRUCT_A]]) align 8 [[B:%.*]], i32 [[I:%.*]]) local_unnamed_addr #[[ATTR0:[0-9]+]] {
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[AGG_TMP52:%.*]] = alloca [[STRUCT_A:%.*]], align 8
+; CHECK-NEXT:    [[AGG_TMP52:%.*]] = alloca [[STRUCT_A]], align 8
 ; CHECK-NEXT:    [[AGG_TMP1:%.*]] = alloca [[STRUCT_A]], align 8
 ; CHECK-NEXT:    [[AGG_TMP:%.*]] = alloca [[STRUCT_A]], align 8
 ; CHECK-NEXT:    [[AGG_TMP5:%.*]] = alloca [[STRUCT_A]], align 8
 ; CHECK-NEXT:    br label [[TAILRECURSE:%.*]]
 ; CHECK:       tailrecurse:
-; CHECK-NEXT:    [[I_TR:%.*]] = phi i32 [ [[I:%.*]], [[ENTRY:%.*]] ], [ [[ADD:%.*]], [[IF_END:%.*]] ]
+; CHECK-NEXT:    [[I_TR:%.*]] = phi i32 [ [[I]], [[ENTRY:%.*]] ], [ [[ADD:%.*]], [[IF_END:%.*]] ]
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[I_TR]], 10
 ; CHECK-NEXT:    br i1 [[CMP]], label [[RETURN:%.*]], label [[IF_END]]
 ; CHECK:       if.end:
-; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds [[STRUCT_A]], ptr [[A:%.*]], i64 0, i32 0, i64 5
+; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds [[STRUCT_A]], ptr [[A]], i64 0, i32 0, i64 5
 ; CHECK-NEXT:    [[TMP0:%.*]] = load i64, ptr [[ARRAYIDX]], align 8
 ; CHECK-NEXT:    [[INC:%.*]] = add nsw i64 [[TMP0]], 1
 ; CHECK-NEXT:    store i64 [[INC]], ptr [[ARRAYIDX]], align 8
-; CHECK-NEXT:    [[ARRAYIDX4:%.*]] = getelementptr inbounds [[STRUCT_A]], ptr [[B:%.*]], i64 0, i32 0, i64 5
+; CHECK-NEXT:    [[ARRAYIDX4:%.*]] = getelementptr inbounds [[STRUCT_A]], ptr [[B]], i64 0, i32 0, i64 5
 ; CHECK-NEXT:    [[TMP1:%.*]] = load i64, ptr [[ARRAYIDX4]], align 8
 ; CHECK-NEXT:    [[CALL:%.*]] = tail call i32 (ptr, ...) @printf(ptr nonnull dereferenceable(1) @.str, i64 [[INC]], i64 [[TMP1]])
 ; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 80, ptr nonnull [[AGG_TMP]])
@@ -101,13 +102,13 @@ declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #2
 
 ; Function Attrs: noinline norecurse nounwind optnone uwtable
 define dso_local i32 @main() local_unnamed_addr #3 {
-; CHECK-LABEL: @main(
+; CHECK-LABEL: define {{[^@]+}}@main() local_unnamed_addr {
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[AGG_TMP:%.*]] = alloca [[STRUCT_A:%.*]], align 8
 ; CHECK-NEXT:    [[AGG_TMP1:%.*]] = alloca [[STRUCT_A]], align 8
 ; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 8 [[AGG_TMP]], ptr align 8 @global, i64 80, i1 false)
 ; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 8 [[AGG_TMP1]], ptr align 8 @global, i64 80, i1 false)
-; CHECK-NEXT:    tail call void @_Z7dostuff1AS_i(ptr byval(%struct.A) align 8 [[AGG_TMP]], ptr byval(%struct.A) align 8 [[AGG_TMP1]], i32 0)
+; CHECK-NEXT:    tail call void @_Z7dostuff1AS_i(ptr byval([[STRUCT_A]]) align 8 [[AGG_TMP]], ptr byval([[STRUCT_A]]) align 8 [[AGG_TMP1]], i32 0)
 ; CHECK-NEXT:    ret i32 0
 ;
 entry:

llvm/test/Transforms/TailCallElim/tre-byval-parameter.ll

@@ -1,4 +1,4 @@
-; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --function-signature
 ; RUN: opt < %s -passes=tailcallelim -verify-dom-info -S | FileCheck %s
 
 ; the test was generated from the following C++ source:
@@ -24,21 +24,22 @@
 
 ; Function Attrs: uwtable
 define dso_local i32 @_Z3fooi1S(i32 %count, ptr nocapture readonly byval(%struct.S) align 8 %p1) local_unnamed_addr #0 {
-; CHECK-LABEL: @_Z3fooi1S(
+; CHECK-LABEL: define {{[^@]+}}@_Z3fooi1S
+; CHECK-SAME: (i32 [[COUNT:%.*]], ptr nocapture byval([[STRUCT_S:%.*]]) align 8 [[P1:%.*]]) local_unnamed_addr #[[ATTR0:[0-9]+]] {
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[AGG_TMP_I1:%.*]] = alloca [[STRUCT_S:%.*]], align 8
+; CHECK-NEXT:    [[AGG_TMP_I1:%.*]] = alloca [[STRUCT_S]], align 8
 ; CHECK-NEXT:    [[AGG_TMP_I:%.*]] = alloca [[STRUCT_S]], align 8
 ; CHECK-NEXT:    [[AGG_TMP14:%.*]] = alloca [[STRUCT_S]], align 8
 ; CHECK-NEXT:    [[AGG_TMP:%.*]] = alloca [[STRUCT_S]], align 8
 ; CHECK-NEXT:    [[AGG_TMP1:%.*]] = alloca [[STRUCT_S]], align 8
 ; CHECK-NEXT:    br label [[TAILRECURSE:%.*]]
 ; CHECK:       tailrecurse:
-; CHECK-NEXT:    [[COUNT_TR:%.*]] = phi i32 [ [[COUNT:%.*]], [[ENTRY:%.*]] ], [ [[ADD:%.*]], [[IF_END:%.*]] ]
+; CHECK-NEXT:    [[COUNT_TR:%.*]] = phi i32 [ [[COUNT]], [[ENTRY:%.*]] ], [ [[ADD:%.*]], [[IF_END:%.*]] ]
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[COUNT_TR]], 10
 ; CHECK-NEXT:    br i1 [[CMP]], label [[IF_THEN:%.*]], label [[IF_END]]
 ; CHECK:       if.then:
-; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr nonnull align 8 dereferenceable(20) [[AGG_TMP]], ptr nonnull align 8 dereferenceable(20) [[P1:%.*]], i64 20, i1 false)
-; CHECK-NEXT:    [[CALL:%.*]] = tail call i32 @_Z3zoo1S(ptr nonnull byval(%struct.S) align 8 [[AGG_TMP]])
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr nonnull align 8 dereferenceable(20) [[AGG_TMP]], ptr nonnull align 8 dereferenceable(20) [[P1]], i64 20, i1 false)
+; CHECK-NEXT:    [[CALL:%.*]] = tail call i32 @_Z3zoo1S(ptr nonnull byval([[STRUCT_S]]) align 8 [[AGG_TMP]])
 ; CHECK-NEXT:    br label [[RETURN:%.*]]
 ; CHECK:       if.end:
 ; CHECK-NEXT:    [[ADD]] = add nsw i32 [[COUNT_TR]], 1