[llvm] r230269 - X86: Use 'mov' instead of 'lea' in Win64 SEH prologues when possible

[David Majnemer]

Author: majnemer
Date: Mon Feb 23 15:50:27 2015
New Revision: 230269

URL: http://llvm.org/viewvc/llvm-project?rev=230269&view=rev
Log:
X86: Use 'mov' instead of 'lea' in Win64 SEH prologues when possible

'mov' and 'lea' are equivalent when the displacement applied with 'lea'
is zero.  However, 'mov' should encode smaller.

Modified:
    llvm/trunk/lib/Target/X86/X86FrameLowering.cpp
    llvm/trunk/test/CodeGen/X86/frameaddr.ll
    llvm/trunk/test/CodeGen/X86/win64_frame.ll

Modified: llvm/trunk/lib/Target/X86/X86FrameLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86FrameLowering.cpp?rev=230269&r1=230268&r2=230269&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86FrameLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86FrameLowering.cpp Mon Feb 23 15:50:27 2015
@@ -863,8 +863,11 @@ void X86FrameLowering::emitPrologue(Mach
   int SEHFrameOffset = 0;
   if (IsWinEH && HasFP) {
     SEHFrameOffset = calculateSetFPREG(NumBytes);
-    addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::LEA64r), FramePtr),
-                 StackPtr, false, SEHFrameOffset);
+    if (SEHFrameOffset)
+      addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::LEA64r), FramePtr),
+                   StackPtr, false, SEHFrameOffset);
+    else
+      BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64rr), FramePtr).addReg(StackPtr);
 
     if (NeedsWinEH)
       BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_SetFrame))

Modified: llvm/trunk/test/CodeGen/X86/frameaddr.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/frameaddr.ll?rev=230269&r1=230268&r2=230269&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/frameaddr.ll (original)
+++ llvm/trunk/test/CodeGen/X86/frameaddr.ll Mon Feb 23 15:50:27 2015
@@ -18,7 +18,7 @@ entry:
 ; CHECK-32-NEXT:  ret
 ; CHECK-W64-LABEL: test1
 ; CHECK-W64:       push
-; CHECK-W64-NEXT:  leaq (%rsp), %rbp
+; CHECK-W64-NEXT:  movq %rsp, %rbp
 ; CHECK-W64-NEXT:  leaq (%rbp), %rax
 ; CHECK-W64-NEXT:  pop
 ; CHECK-W64-NEXT:  ret
@@ -53,7 +53,7 @@ entry:
 ; CHECK-32-NEXT:  ret
 ; CHECK-W64-LABEL: test2
 ; CHECK-W64:       push
-; CHECK-W64-NEXT:  leaq (%rsp), %rbp
+; CHECK-W64-NEXT:  movq %rsp, %rbp
 ; CHECK-W64-NEXT:  leaq (%rbp), %rax
 ; CHECK-W64-NEXT:  pop
 ; CHECK-W64-NEXT:  ret

Modified: llvm/trunk/test/CodeGen/X86/win64_frame.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/win64_frame.ll?rev=230269&r1=230268&r2=230269&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/win64_frame.ll (original)
+++ llvm/trunk/test/CodeGen/X86/win64_frame.ll Mon Feb 23 15:50:27 2015
@@ -9,7 +9,7 @@ define i32 @f1(i32 %p1, i32 %p2, i32 %p3
 define void @f2(i32 %p, ...) "no-frame-pointer-elim"="true" {
   ; CHECK-LABEL: f2:
   ; CHECK:      .seh_stackalloc 8
-  ; CHECK:      leaq    (%rsp), %rbp
+  ; CHECK:      movq    %rsp, %rbp
   ; CHECK:      .seh_setframe 5, 0
   ; CHECK:      movq    %rdx, 32(%rbp)
   ; CHECK:      leaq    32(%rbp), %rax
@@ -20,7 +20,7 @@ define void @f2(i32 %p, ...) "no-frame-p
 
 define i8* @f3() "no-frame-pointer-elim"="true" {
   ; CHECK-LABEL: f3:
-  ; CHECK:      leaq    (%rsp), %rbp
+  ; CHECK:      movq    %rsp, %rbp
   ; CHECK:      .seh_setframe 5, 0
   ; CHECK:      movq    8(%rbp), %rax
   %ra = call i8* @llvm.returnaddress(i32 0)