[WinEH] Give up on using CSRs across 32-bit invokes for now

The runtime does not restore CSRs when transferring control back to the
function handling the exception. According to the experts on IRC, LLVM's
register allocator has no way to model register clobbers that only
happen on one edge of the CFG. For now, don't worry about trying to use
the meager three CSRs available on 32-bit X86 and just say that such
invokes preserve nothing.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241865 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 74e5dd62ccb2fe54880e896d83e92007eae9cf57..2e689fbe3d9e86954aefda4099c0e8e4502b3373 100644 (file)
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -3258,9 +3258,24 @@ X86TargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
                                   RegsToPass[i].second.getValueType()));
 
   // Add a register mask operand representing the call-preserved registers.
-  const TargetRegisterInfo *TRI = Subtarget->getRegisterInfo();
-  const uint32_t *Mask = TRI->getCallPreservedMask(MF, CallConv);
+  const uint32_t *Mask = RegInfo->getCallPreservedMask(MF, CallConv);
   assert(Mask && "Missing call preserved mask for calling convention");
+
+  // If this is an invoke in a 32-bit function using an MSVC personality, assume
+  // the function clobbers all registers. If an exception is thrown, the runtime
+  // will not restore CSRs.
+  // FIXME: Model this more precisely so that we can register allocate across
+  // the normal edge and spill and fill across the exceptional edge.
+  if (!Is64Bit && CLI.CS && CLI.CS->isInvoke()) {
+    const Function *CallerFn = MF.getFunction();
+    EHPersonality Pers =
+        CallerFn->hasPersonalityFn()
+            ? classifyEHPersonality(CallerFn->getPersonalityFn())
+            : EHPersonality::Unknown;
+    if (isMSVCEHPersonality(Pers))
+      Mask = RegInfo->getNoPreservedMask();
+  }
+
   Ops.push_back(DAG.getRegisterMask(Mask));
 
   if (InFlag.getNode())

diff --git a/test/CodeGen/X86/seh-catch-all-win32.ll b/test/CodeGen/X86/seh-catch-all-win32.ll
index d840cb41acc8bfe31686c31adc5f2096e62655fd..39906f8fecc5dfef83e8caf99b32d49b13a34d80 100644 (file)
--- a/test/CodeGen/X86/seh-catch-all-win32.ll
+++ b/test/CodeGen/X86/seh-catch-all-win32.ll
@@ -59,20 +59,31 @@ entry:
 ; Check that we can get the exception code from eax to the printf.
 
 ; CHECK-LABEL: _main:
+; CHECK: pushl %ebp
+; CHECK: movl %esp, %ebp
+;       Ensure that we push *all* the CSRs, since they are clobbered by the
+;       __except block.
+; CHECK: pushl %ebx
+; CHECK: pushl %edi
+; CHECK: pushl %esi
+
 ; CHECK: Lmain$frame_escape_0 = [[code_offs:[-0-9]+]]
 ; CHECK: Lmain$frame_escape_1 = [[reg_offs:[-0-9]+]]
 ; CHECK: movl %esp, [[reg_offs]](%ebp)
 ; CHECK: movl $L__ehtable$main,
 ;      EH state 0
-; CHECK: movl $0, -4(%ebp)
+; CHECK: movl $0, -16(%ebp)
 ; CHECK: calll _crash
+; CHECK: popl %esi
+; CHECK: popl %edi
+; CHECK: popl %ebx
 ; CHECK: retl
 ; CHECK: # Block address taken
 ;      stackrestore
-; CHECK: movl [[reg_offs]](%ebp), %esp
+; CHECK: movl -24(%ebp), %esp
 ;      EH state -1
 ; CHECK: movl [[code_offs]](%ebp), %[[code:[a-z]+]]
-; CHECK: movl $-1, -4(%ebp)
+; CHECK: movl $-1, -16(%ebp)
 ; CHECK-DAG: movl %[[code]], 4(%esp)
 ; CHECK-DAG: movl $_str, (%esp)
 ; CHECK: calll _printf

diff --git a/test/CodeGen/X86/win32-eh.ll b/test/CodeGen/X86/win32-eh.ll
index f235d2884d03b80d43f5f1e92a8cbffa46f05256..199afd07f797b41f9075d5e2675184b33fcd3aa0 100644 (file)
--- a/test/CodeGen/X86/win32-eh.ll
+++ b/test/CodeGen/X86/win32-eh.ll
@@ -32,16 +32,19 @@ eh.resume:
 ; CHECK-LABEL: _use_except_handler3:
 ; CHECK: pushl %ebp
 ; CHECK: movl %esp, %ebp
+; CHECK: pushl %ebx
+; CHECK: pushl %edi
+; CHECK: pushl %esi
 ; CHECK: subl ${{[0-9]+}}, %esp
-; CHECK: movl $-1, -4(%ebp)
-; CHECK: movl $L__ehtable$use_except_handler3, -8(%ebp)
-; CHECK: leal -16(%ebp), %[[node:[^ ,]*]]
-; CHECK: movl $__except_handler3, -12(%ebp)
+; CHECK: movl $-1, -16(%ebp)
+; CHECK: movl $L__ehtable$use_except_handler3, -20(%ebp)
+; CHECK: leal -28(%ebp), %[[node:[^ ,]*]]
+; CHECK: movl $__except_handler3, -24(%ebp)
 ; CHECK: movl %fs:0, %[[next:[^ ,]*]]
-; CHECK: movl %[[next]], -16(%ebp)
+; CHECK: movl %[[next]], -28(%ebp)
 ; CHECK: movl %[[node]], %fs:0
 ; CHECK: calll _may_throw_or_crash
-; CHECK: movl -16(%ebp), %[[next:[^ ,]*]]
+; CHECK: movl -28(%ebp), %[[next:[^ ,]*]]
 ; CHECK: movl %[[next]], %fs:0
 ; CHECK: retl
 
@@ -72,18 +75,18 @@ eh.resume:
 ; CHECK: pushl %ebp
 ; CHECK: movl %esp, %ebp
 ; CHECK: subl ${{[0-9]+}}, %esp
-; CHECK: movl %esp, -24(%ebp)
-; CHECK: movl $-2, -4(%ebp)
+; CHECK: movl %esp, -36(%ebp)
+; CHECK: movl $-2, -16(%ebp)
 ; CHECK: movl $L__ehtable$use_except_handler4, %[[lsda:[^ ,]*]]
 ; CHECK: xorl ___security_cookie, %[[lsda]]
-; CHECK: movl %[[lsda]], -8(%ebp)
-; CHECK: leal -16(%ebp), %[[node:[^ ,]*]]
-; CHECK: movl $__except_handler4, -12(%ebp)
+; CHECK: movl %[[lsda]], -20(%ebp)
+; CHECK: leal -28(%ebp), %[[node:[^ ,]*]]
+; CHECK: movl $__except_handler4, -24(%ebp)
 ; CHECK: movl %fs:0, %[[next:[^ ,]*]]
-; CHECK: movl %[[next]], -16(%ebp)
+; CHECK: movl %[[next]], -28(%ebp)
 ; CHECK: movl %[[node]], %fs:0
 ; CHECK: calll _may_throw_or_crash
-; CHECK: movl -16(%ebp), %[[next:[^ ,]*]]
+; CHECK: movl -28(%ebp), %[[next:[^ ,]*]]
 ; CHECK: movl %[[next]], %fs:0
 ; CHECK: retl
 
@@ -115,16 +118,16 @@ catchall:
 ; CHECK: pushl %ebp
 ; CHECK: movl %esp, %ebp
 ; CHECK: subl ${{[0-9]+}}, %esp
-; CHECK: movl %esp, -16(%ebp)
-; CHECK: movl $-1, -4(%ebp)
-; CHECK: leal -12(%ebp), %[[node:[^ ,]*]]
-; CHECK: movl $___ehhandler$use_CxxFrameHandler3, -8(%ebp)
+; CHECK: movl %esp, -28(%ebp)
+; CHECK: movl $-1, -16(%ebp)
+; CHECK: leal -24(%ebp), %[[node:[^ ,]*]]
+; CHECK: movl $___ehhandler$use_CxxFrameHandler3, -20(%ebp)
 ; CHECK: movl %fs:0, %[[next:[^ ,]*]]
-; CHECK: movl %[[next]], -12(%ebp)
+; CHECK: movl %[[next]], -24(%ebp)
 ; CHECK: movl %[[node]], %fs:0
-; CHECK: movl $0, -4(%ebp)
+; CHECK: movl $0, -16(%ebp)
 ; CHECK: calll _may_throw_or_crash
-; CHECK: movl -12(%ebp), %[[next:[^ ,]*]]
+; CHECK: movl -24(%ebp), %[[next:[^ ,]*]]
 ; CHECK: movl %[[next]], %fs:0
 ; CHECK: retl