[PATCH] D128960: [BOLT] Fix instrumentation problem with floating point

[Maksim Panchenko via Phabricator via llvm-commits]

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If BOLT instrumentation runtime uses XMM registers, it can interfere
with the user program causing crashes and unexpected behavior. This
happens as the instrumentation code preserves general purpose registers
only.

Build BOLT instrumentation runtime with "-mno-sse".


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D128960

Files:
  bolt/runtime/CMakeLists.txt
  bolt/test/runtime/X86/instrumentation-xmm.c


Index: bolt/test/runtime/X86/instrumentation-xmm.c
===================================================================
--- /dev/null
+++ bolt/test/runtime/X86/instrumentation-xmm.c
@@ -0,0 +1,25 @@
+#include <stdio.h>
+
+void foo(float a) {
+  printf("a = %f\n", a);
+}
+
+typedef void (*fptr_t)(float);
+fptr_t func = foo;
+
+int main() {
+  func(42);
+  return 0;
+}
+
+/*
+## Check that BOLT instrumentation runtime preserves xmm registers.
+
+REQUIRES: system-linux,bolt-runtime
+
+RUN: %clang %cflags %s -o %t.exe -fno-inline -Wl,-q
+RUN: llvm-bolt %t.exe --instrument -o %t.instrumented
+RUN: %t.instrumented | FileCheck %s
+
+CHECK: a = 42.000000
+*/
Index: bolt/runtime/CMakeLists.txt
===================================================================
--- bolt/runtime/CMakeLists.txt
+++ bolt/runtime/CMakeLists.txt
@@ -23,7 +23,8 @@
   -ffreestanding
   -fno-exceptions
   -fno-rtti
-  -fno-stack-protector)
+  -fno-stack-protector
+  -mno-sse)
 
 # Don't let the compiler think it can create calls to standard libs
 target_compile_options(bolt_rt_instr PRIVATE ${BOLT_RT_FLAGS} -fPIE)


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