[llvm] r196261 - Enhance the fix of PR17631
Michael Liao
michael.liao at intel.com
Tue Dec 3 01:17:32 PST 2013
Author: hliao
Date: Tue Dec 3 03:17:32 2013
New Revision: 196261
URL: http://llvm.org/viewvc/llvm-project?rev=196261&view=rev
Log:
Enhance the fix of PR17631
- The fix to PR17631 fixes part of the cases where 'vzeroupper' should
not be issued before 'call' insn. There're other cases where helper
calls will be inserted not limited to epilog. These helper calls do
not follow the standard calling convention and won't clobber any YMM
registers. (So far, all call conventions will clobber any or part of
YMM registers.)
This patch enhances the previous fix to cover more cases 'vzerosupper' should
not be inserted by checking if that function call won't clobber any YMM
registers and skipping it if so.
Modified:
llvm/trunk/lib/Target/X86/X86VZeroUpper.cpp
llvm/trunk/test/CodeGen/X86/pr17631.ll
Modified: llvm/trunk/lib/Target/X86/X86VZeroUpper.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86VZeroUpper.cpp?rev=196261&r1=196260&r2=196261&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86VZeroUpper.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86VZeroUpper.cpp Tue Dec 3 03:17:32 2013
@@ -148,6 +148,25 @@ static bool hasYmmReg(MachineInstr *MI)
return false;
}
+/// clobbersAnyYmmReg() - Check if any YMM register will be clobbered by this
+/// instruction.
+static bool clobbersAnyYmmReg(MachineInstr *MI) {
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ const MachineOperand &MO = MI->getOperand(i);
+ if (!MO.isRegMask())
+ continue;
+ for (unsigned reg = X86::YMM0; reg < X86::YMM31; ++reg) {
+ if (MO.clobbersPhysReg(reg))
+ return true;
+ }
+ for (unsigned reg = X86::ZMM0; reg < X86::ZMM31; ++reg) {
+ if (MO.clobbersPhysReg(reg))
+ return true;
+ }
+ }
+ return false;
+}
+
/// runOnMachineFunction - Loop over all of the basic blocks, inserting
/// vzero upper instructions before function calls.
bool VZeroUpperInserter::runOnMachineFunction(MachineFunction &MF) {
@@ -234,14 +253,6 @@ bool VZeroUpperInserter::processBasicBlo
DebugLoc dl = I->getDebugLoc();
MachineInstr *MI = I;
- // Don't need to check instructions added in prolog.
- // In prolog, special function calls may be added for specific targets
- // (e.g. on Windows, a prolog helper '_chkstk' is called when the local
- // variables exceed 4K bytes on stack.) These helpers won't use/def YMM/XMM
- // registers.
- if (MI->getFlag(MachineInstr::FrameSetup))
- continue;
-
bool isControlFlow = MI->isCall() || MI->isReturn();
// Shortcut: don't need to check regular instructions in dirty state.
@@ -260,6 +271,14 @@ bool VZeroUpperInserter::processBasicBlo
if (!isControlFlow)
continue;
+ // If the call won't clobber any YMM register, skip it as well. It usually
+ // happens on helper function calls (such as '_chkstk', '_ftol2') where
+ // standard calling convention is not used (RegMask is not used to mark
+ // register clobbered and register usage (def/imp-def/use) is well-dfined
+ // and explicitly specified.
+ if (MI->isCall() && !clobbersAnyYmmReg(MI))
+ continue;
+
BBHasCall = true;
// The VZEROUPPER instruction resets the upper 128 bits of all Intel AVX
Modified: llvm/trunk/test/CodeGen/X86/pr17631.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/pr17631.ll?rev=196261&r1=196260&r2=196261&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/pr17631.ll (original)
+++ llvm/trunk/test/CodeGen/X86/pr17631.ll Tue Dec 3 03:17:32 2013
@@ -1,16 +1,16 @@
; RUN: llc < %s -mcpu=core-avx-i -mtriple=i386-pc-win32 | FileCheck %s
-
+
%struct_type = type { [64 x <8 x float>], <8 x float> }
-
+
; Function Attrs: nounwind readnone
declare i32 @llvm.x86.avx.movmsk.ps.256(<8 x float>)
-
+
; Function Attrs: nounwind
define i32 @equal(<8 x i32> %A) {
allocas:
%first_alloc = alloca [64 x <8 x i32>]
%second_alloc = alloca %struct_type
-
+
%A1 = bitcast <8 x i32> %A to <8 x float>
%A2 = call i32 @llvm.x86.avx.movmsk.ps.256(<8 x float> %A1)
ret i32 %A2
@@ -20,3 +20,15 @@ allocas:
; CHECK-NOT: vzeroupper
; CHECK: _chkstk
; CHECK: ret
+
+define <8 x float> @foo(<8 x float> %y, i64* %p, double %x) {
+ %i = fptoui double %x to i64
+ store i64 %i, i64* %p
+ %ret = fadd <8 x float> %y, %y
+ ret <8 x float> %ret
+}
+
+; CHECK: foo
+; CHECK-NOT: vzeroupper
+; CHECK: _ftol2
+; CHECK: ret
More information about the llvm-commits
mailing list