SafeStack: Emit __safestack_pointer_address call through RuntimeLibcalls #147916

arsenm · 2025-07-10T07:58:08Z

Stop using hardcoded function named and check availability. This only fixes
the forced usage via command line in the pass itself; the implementations
inside of TargetLoweringBase hide additional call emission.

arsenm · 2025-07-10T07:58:23Z

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llvmbot · 2025-07-10T08:02:20Z

@llvm/pr-subscribers-llvm-transforms

@llvm/pr-subscribers-backend-nvptx

Author: Matt Arsenault (arsenm)

Changes

Stop using hardcoded function named and check availability. This only fixes
the forced usage via command line in the pass itself; the implementations
inside of TargetLoweringBase hide additional call emission.

Full diff: https://github.com/llvm/llvm-project/pull/147916.diff

4 Files Affected:

(modified) llvm/include/llvm/IR/RuntimeLibcalls.td (+6)
(modified) llvm/lib/CodeGen/SafeStack.cpp (+9-1)
(modified) llvm/lib/IR/RuntimeLibcalls.cpp (+5)
(added) llvm/test/Transforms/SafeStack/NVPTX/safestack-pointer-address-libcall-error.ll (+12)

diff --git a/llvm/include/llvm/IR/RuntimeLibcalls.td b/llvm/include/llvm/IR/RuntimeLibcalls.td
index 29de1206a8974..2c26c05402e4e 100644
--- a/llvm/include/llvm/IR/RuntimeLibcalls.td
+++ b/llvm/include/llvm/IR/RuntimeLibcalls.td
@@ -339,6 +339,9 @@ defset list<RuntimeLibcall> LibCalls__OutOfLineAtomic = {
 def STACKPROTECTOR_CHECK_FAIL : RuntimeLibcall;
 def STACK_SMASH_HANDLER : RuntimeLibcall;
 
+// Safe stack
+def SAFESTACK_POINTER_ADDRESS : RuntimeLibcall;
+
 // Deoptimization
 def DEOPTIMIZE : RuntimeLibcall;
 
@@ -656,6 +659,9 @@ foreach lc = LibCalls__atomic in {
 // Stack Protector Fail
 def __stack_chk_fail : RuntimeLibcallImpl<STACKPROTECTOR_CHECK_FAIL>;
 
+// Safe stack.
+def __safestack_pointer_address : RuntimeLibcallImpl<SAFESTACK_POINTER_ADDRESS>;
+
 // Deoptimization
 def __llvm_deoptimize : RuntimeLibcallImpl<DEOPTIMIZE>;
 
diff --git a/llvm/lib/CodeGen/SafeStack.cpp b/llvm/lib/CodeGen/SafeStack.cpp
index a6c1a76f53f39..996207034d076 100644
--- a/llvm/lib/CodeGen/SafeStack.cpp
+++ b/llvm/lib/CodeGen/SafeStack.cpp
@@ -799,8 +799,16 @@ bool SafeStack::run() {
     IRB.SetCurrentDebugLocation(
         DILocation::get(SP->getContext(), SP->getScopeLine(), 0, SP));
   if (SafeStackUsePointerAddress) {
+    const char *SafestackPointerAddressName =
+        TL.getLibcallName(RTLIB::SAFESTACK_POINTER_ADDRESS);
+    if (!SafestackPointerAddressName) {
+      F.getContext().emitError(
+          "no libcall available for safestack pointer address");
+      return false;
+    }
+
     FunctionCallee Fn = F.getParent()->getOrInsertFunction(
-        "__safestack_pointer_address", IRB.getPtrTy(0));
+        SafestackPointerAddressName, IRB.getPtrTy(0));
     UnsafeStackPtr = IRB.CreateCall(Fn);
   } else {
     UnsafeStackPtr = TL.getSafeStackPointerLocation(IRB);
diff --git a/llvm/lib/IR/RuntimeLibcalls.cpp b/llvm/lib/IR/RuntimeLibcalls.cpp
index f9bd9b6029234..21e8fdb9f7feb 100644
--- a/llvm/lib/IR/RuntimeLibcalls.cpp
+++ b/llvm/lib/IR/RuntimeLibcalls.cpp
@@ -293,6 +293,11 @@ void RuntimeLibcallsInfo::initLibcalls(const Triple &TT,
     setLibcallImpl(RTLIB::POWI_F64, RTLIB::Unsupported);
   }
 
+  if (TT.isAndroid()) {
+    setLibcallImpl(RTLIB::SAFESTACK_POINTER_ADDRESS,
+                   RTLIB::__safestack_pointer_address);
+  }
+
   // Setup Windows compiler runtime calls.
   if (TT.getArch() == Triple::x86 &&
       (TT.isWindowsMSVCEnvironment() || TT.isWindowsItaniumEnvironment())) {
diff --git a/llvm/test/Transforms/SafeStack/NVPTX/safestack-pointer-address-libcall-error.ll b/llvm/test/Transforms/SafeStack/NVPTX/safestack-pointer-address-libcall-error.ll
new file mode 100644
index 0000000000000..9bf84585e5468
--- /dev/null
+++ b/llvm/test/Transforms/SafeStack/NVPTX/safestack-pointer-address-libcall-error.ll
@@ -0,0 +1,12 @@
+; RUN: not opt -disable-output -mtriple=nvptx64-- -safestack-use-pointer-address -mcpu=sm_90 -passes=safe-stack %s 2>&1 | FileCheck %s
+
+; CHECK: error: no libcall available for safestack pointer address
+define void @foo(i32 %t) #0 {
+  %vla = alloca i32, i32 %t, align 4
+  call void @baz(ptr %vla)
+  ret void
+}
+
+declare void @baz(ptr)
+
+attributes #0 = { nounwind safestack sspstrong }

llvmbot · 2025-07-10T08:02:21Z

@llvm/pr-subscribers-llvm-ir

Author: Matt Arsenault (arsenm)

Changes

Stop using hardcoded function named and check availability. This only fixes
the forced usage via command line in the pass itself; the implementations
inside of TargetLoweringBase hide additional call emission.

Full diff: https://github.com/llvm/llvm-project/pull/147916.diff

4 Files Affected:

(modified) llvm/include/llvm/IR/RuntimeLibcalls.td (+6)
(modified) llvm/lib/CodeGen/SafeStack.cpp (+9-1)
(modified) llvm/lib/IR/RuntimeLibcalls.cpp (+5)
(added) llvm/test/Transforms/SafeStack/NVPTX/safestack-pointer-address-libcall-error.ll (+12)

diff --git a/llvm/include/llvm/IR/RuntimeLibcalls.td b/llvm/include/llvm/IR/RuntimeLibcalls.td
index 29de1206a8974..2c26c05402e4e 100644
--- a/llvm/include/llvm/IR/RuntimeLibcalls.td
+++ b/llvm/include/llvm/IR/RuntimeLibcalls.td
@@ -339,6 +339,9 @@ defset list<RuntimeLibcall> LibCalls__OutOfLineAtomic = {
 def STACKPROTECTOR_CHECK_FAIL : RuntimeLibcall;
 def STACK_SMASH_HANDLER : RuntimeLibcall;
 
+// Safe stack
+def SAFESTACK_POINTER_ADDRESS : RuntimeLibcall;
+
 // Deoptimization
 def DEOPTIMIZE : RuntimeLibcall;
 
@@ -656,6 +659,9 @@ foreach lc = LibCalls__atomic in {
 // Stack Protector Fail
 def __stack_chk_fail : RuntimeLibcallImpl<STACKPROTECTOR_CHECK_FAIL>;
 
+// Safe stack.
+def __safestack_pointer_address : RuntimeLibcallImpl<SAFESTACK_POINTER_ADDRESS>;
+
 // Deoptimization
 def __llvm_deoptimize : RuntimeLibcallImpl<DEOPTIMIZE>;
 
diff --git a/llvm/lib/CodeGen/SafeStack.cpp b/llvm/lib/CodeGen/SafeStack.cpp
index a6c1a76f53f39..996207034d076 100644
--- a/llvm/lib/CodeGen/SafeStack.cpp
+++ b/llvm/lib/CodeGen/SafeStack.cpp
@@ -799,8 +799,16 @@ bool SafeStack::run() {
     IRB.SetCurrentDebugLocation(
         DILocation::get(SP->getContext(), SP->getScopeLine(), 0, SP));
   if (SafeStackUsePointerAddress) {
+    const char *SafestackPointerAddressName =
+        TL.getLibcallName(RTLIB::SAFESTACK_POINTER_ADDRESS);
+    if (!SafestackPointerAddressName) {
+      F.getContext().emitError(
+          "no libcall available for safestack pointer address");
+      return false;
+    }
+
     FunctionCallee Fn = F.getParent()->getOrInsertFunction(
-        "__safestack_pointer_address", IRB.getPtrTy(0));
+        SafestackPointerAddressName, IRB.getPtrTy(0));
     UnsafeStackPtr = IRB.CreateCall(Fn);
   } else {
     UnsafeStackPtr = TL.getSafeStackPointerLocation(IRB);
diff --git a/llvm/lib/IR/RuntimeLibcalls.cpp b/llvm/lib/IR/RuntimeLibcalls.cpp
index f9bd9b6029234..21e8fdb9f7feb 100644
--- a/llvm/lib/IR/RuntimeLibcalls.cpp
+++ b/llvm/lib/IR/RuntimeLibcalls.cpp
@@ -293,6 +293,11 @@ void RuntimeLibcallsInfo::initLibcalls(const Triple &TT,
     setLibcallImpl(RTLIB::POWI_F64, RTLIB::Unsupported);
   }
 
+  if (TT.isAndroid()) {
+    setLibcallImpl(RTLIB::SAFESTACK_POINTER_ADDRESS,
+                   RTLIB::__safestack_pointer_address);
+  }
+
   // Setup Windows compiler runtime calls.
   if (TT.getArch() == Triple::x86 &&
       (TT.isWindowsMSVCEnvironment() || TT.isWindowsItaniumEnvironment())) {
diff --git a/llvm/test/Transforms/SafeStack/NVPTX/safestack-pointer-address-libcall-error.ll b/llvm/test/Transforms/SafeStack/NVPTX/safestack-pointer-address-libcall-error.ll
new file mode 100644
index 0000000000000..9bf84585e5468
--- /dev/null
+++ b/llvm/test/Transforms/SafeStack/NVPTX/safestack-pointer-address-libcall-error.ll
@@ -0,0 +1,12 @@
+; RUN: not opt -disable-output -mtriple=nvptx64-- -safestack-use-pointer-address -mcpu=sm_90 -passes=safe-stack %s 2>&1 | FileCheck %s
+
+; CHECK: error: no libcall available for safestack pointer address
+define void @foo(i32 %t) #0 {
+  %vla = alloca i32, i32 %t, align 4
+  call void @baz(ptr %vla)
+  ret void
+}
+
+declare void @baz(ptr)
+
+attributes #0 = { nounwind safestack sspstrong }

arsenm · 2025-07-15T09:34:03Z

Merge activity

Jul 15, 9:34 AM UTC: A user started a stack merge that includes this pull request via Graphite.
Jul 15, 9:44 AM UTC: Graphite rebased this pull request as part of a merge.
Jul 15, 9:47 AM UTC: Graphite rebased this pull request as part of a merge.
Jul 15, 9:50 AM UTC: Graphite rebased this pull request as part of a merge.
Jul 15, 9:53 AM UTC: Graphite rebased this pull request as part of a merge.
Jul 15, 9:58 AM UTC: Graphite rebased this pull request as part of a merge.
Jul 15, 10:01 AM UTC: @arsenm merged this pull request with Graphite.

Stop using hardcoded function named and check availability. This only fixes the forced usage via command line in the pass itself; the implementations inside of TargetLoweringBase hide additional call emission.

This was referenced Jul 10, 2025

RuntimeLibcalls: Add some tests for OpenBSD stack protectors #147888

Merged

StackProtector: Use RuntimeLibcalls to query libcall names #147913

Merged

This was referenced Jul 10, 2025

RuntimeLibcalls: Add entries for some exception related functions #147914

Merged

SafeStack: Emit call to __stack_chk_fail through RuntimeLibcalls #147915

Merged

SafeStack: Check if __safestack_pointer_address is available #147917

Merged

arsenm added the llvm:codegen label Jul 10, 2025 — with Graphite App

arsenm requested review from dpaoliello, efriedma-quic, eugenis, MaskRay, pcc and PiJoules July 10, 2025 08:01

arsenm marked this pull request as ready for review July 10, 2025 08:01

llvmbot added backend:NVPTX llvm:ir llvm:transforms labels Jul 10, 2025

MaskRay approved these changes Jul 15, 2025

View reviewed changes

arsenm force-pushed the users/arsenm/safestack/use-runtime-libcalls-__safestack_pointer_address branch from 28d4fc5 to fcf040c Compare July 15, 2025 08:04

arsenm force-pushed the users/arsenm/safestack/use-runtime-libcalls-__stack_chk_fail branch from cb3cf0b to a74db10 Compare July 15, 2025 08:04

arsenm mentioned this pull request Jul 15, 2025

TargetLowering: Replace android triple check with libcall check #148800

Open

arsenm force-pushed the users/arsenm/safestack/use-runtime-libcalls-__stack_chk_fail branch from a74db10 to 3c4dcd4 Compare July 15, 2025 09:41

Base automatically changed from users/arsenm/safestack/use-runtime-libcalls-__stack_chk_fail to main July 15, 2025 09:43

arsenm force-pushed the users/arsenm/safestack/use-runtime-libcalls-__safestack_pointer_address branch 4 times, most recently from 4510a20 to 3ec4dc9 Compare July 15, 2025 09:53

SafeStack: Emit __safestack_pointer_address call through RuntimeLibcalls

b0f33a2

Stop using hardcoded function named and check availability. This only fixes the forced usage via command line in the pass itself; the implementations inside of TargetLoweringBase hide additional call emission.

arsenm force-pushed the users/arsenm/safestack/use-runtime-libcalls-__safestack_pointer_address branch from 3ec4dc9 to b0f33a2 Compare July 15, 2025 09:57

arsenm merged commit 9250139 into main Jul 15, 2025
7 of 9 checks passed

arsenm deleted the users/arsenm/safestack/use-runtime-libcalls-__safestack_pointer_address branch July 15, 2025 10:01

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