[PATCH] D90742: [llvm-exegesis][X86] Save and restore eflags.

[Clement Courbet via Phabricator via llvm-commits]

courbet created this revision.
courbet added a reviewer: gchatelet.
Herald added a subscriber: mstojanovic.
Herald added a project: LLVM.
courbet requested review of this revision.

This is needed to benchmark instruction that touch EFLAGS (e.g. STD: set direction flag).


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D90742

Files:
  llvm/test/tools/llvm-exegesis/X86/uops-STD.s
  llvm/tools/llvm-exegesis/lib/X86/Target.cpp


Index: llvm/tools/llvm-exegesis/lib/X86/Target.cpp
===================================================================
--- llvm/tools/llvm-exegesis/lib/X86/Target.cpp
+++ llvm/tools/llvm-exegesis/lib/X86/Target.cpp
@@ -603,8 +603,10 @@
 #ifdef __x86_64__
 # if defined(_MSC_VER)
     _fxsave64(FPState);
+    Eflags = __readeflags();
 # elif defined(__GNUC__)
     __builtin_ia32_fxsave64(FPState);
+    Eflags = __builtin_ia32_readeflags_u64();
 # endif
 #else
     llvm_unreachable("X86 exegesis running on non-X86 target");
@@ -618,9 +620,11 @@
 # if defined(_MSC_VER)
     _clearfp();
     _fxrstor64(FPState);
+    __writeeflags(Eflags);
 # elif defined(__GNUC__)
     asm volatile("fwait");
     __builtin_ia32_fxrstor64(FPState);
+    __builtin_ia32_writeeflags_u64(Eflags);
 # endif
 #else
     llvm_unreachable("X86 exegesis running on non-X86 target");
@@ -630,6 +634,7 @@
 private:
 #ifdef __x86_64__
   alignas(16) char FPState[512];
+  uint64_t Eflags;
 #endif
 };
 
Index: llvm/test/tools/llvm-exegesis/X86/uops-STD.s
===================================================================
--- /dev/null
+++ llvm/test/tools/llvm-exegesis/X86/uops-STD.s
@@ -0,0 +1,7 @@
+# RUN: llvm-exegesis -mode=uops -opcode-name=STD -repetition-mode=duplicate | FileCheck %s
+# RUN: llvm-exegesis -mode=uops -opcode-name=STD -repetition-mode=loop | FileCheck %s
+
+CHECK:      mode:            uops
+CHECK-NEXT: key:
+CHECK-NEXT:   instructions:
+CHECK-NEXT:     STD


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