nickdesaulniers

--- |
  ; ModuleID = 'regallocfast.g.mir'
  source_filename = "x.c"
  target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
  target triple = "x86_64-unknown-linux-gnu"
  
  ; Function Attrs: noinline nounwind optnone
  define dso_local i32 @main() #0 !dbg !9 {
  entry:
    %retval = alloca i32, align 4

nickdesaulniers

void strncpy_from_kernel_nofault_count() {
  asm goto("" : "=r"(*(char *)0) : : : Efault);
Efault:
}

nickdesaulniers

diff --git a/llvm/include/llvm/IR/Intrinsics.td b/llvm/include/llvm/IR/Intrinsics.td
index 475685d0857d..6090dee6f769 100644
--- a/llvm/include/llvm/IR/Intrinsics.td
+++ b/llvm/include/llvm/IR/Intrinsics.td
@@ -622,7 +622,8 @@ def int_call_preallocated_teardown : DefaultAttrsIntrinsic<[], [llvm_token_ty]>;
 
 // This intrinsic is intentionally undocumented and users shouldn't call it;
 // it's produced then quickly consumed during codegen.
-def int_callbr_landingpad : Intrinsic<[llvm_any_ty], [], [IntrNoMerge]>;
+def int_callbr_landingpad : Intrinsic<[llvm_any_ty], [LLVMMatchType<0>],

nickdesaulniers

perf record -e cycles:pp --call-graph lbr -- clang -Wfoo -c -x c /dev/null

perf report --no-children --sort=dso,symbol --total-cycles

nickdesaulniers

diff --git a/init/Kconfig b/init/Kconfig                                                                                                                                        
index e9119bf54b1f..fce97bfbe452 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -153,7 +153,7 @@ config WERROR
 
 config UAPI_HEADER_TEST
        bool "Compile test UAPI headers"
-       depends on HEADERS_INSTALL && CC_CAN_LINK
+       depends on HEADERS_INSTALL

nickdesaulniers

--- slab.before.clang.txt       2022-02-14 14:40:46.324688583 -0800
+++ slab.after.clang.bad.txt    2022-02-14 15:05:43.610957545 -0800
@@ -5,64 +5,57 @@
 Disassembly of section .text:
 
 <kmem_cache_free>:
+       push   %rbp
+       mov    %rsp,%rbp
        push   %r15
        push   %r14

nickdesaulniers

--- slab.before.clang.txt       2022-02-14 14:40:46.324688583 -0800
+++ slab.after.clang.txt        2022-02-14 14:40:27.824562293 -0800
@@ -8,61 +8,51 @@
        push   %r15
        push   %r14
        push   %rbx
-       sub    $0x10,%rsp
-       mov    %gs:0x28,%rax
-       mov    %rax,0x8(%rsp)
        test   %rdi,%rdi

nickdesaulniers

#!/usr/bin/env sh

function pretty_print() {
    printf "%b%s\033[0m" "${1}" "${2}"
    shift 2
    while ((${#})); do
        printf "%b" "${1}"
        shift
    done
    printf '\n'

nickdesaulniers

diff --git a/kernel/panic.c b/kernel/panic.c
index cefd7d82366f..f664d9682668 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -681,10 +681,11 @@ device_initcall(register_warn_debugfs);
  */
 __visible noinstr void __stack_chk_fail(void)
 {
-       instrumentation_begin();
+begin:

nickdesaulniers

diff --git a/arch/x86/include/asm/bug.h b/arch/x86/include/asm/bug.h
index 84b87538a15d..6e3433c64eae 100644
--- a/arch/x86/include/asm/bug.h
+++ b/arch/x86/include/asm/bug.h
@@ -22,7 +22,7 @@
 
 #ifdef CONFIG_DEBUG_BUGVERBOSE
 
-#define _BUG_FLAGS(ins, flags)                                         \
+#define _BUG_FLAGS(ins, flags, extra)                                  \