[llvm] [X86] Stop adding liveins for virtual registers in emitStackProbeInlineWindowsCoreCLR64. (PR #106828)

[Craig Topper via llvm-commits]

https://github.com/topperc updated https://github.com/llvm/llvm-project/pull/106828

>From 67aae0049c694e3619909d440500dc360ae74c51 Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper at sifive.com>
Date: Fri, 30 Aug 2024 22:47:03 -0700
Subject: [PATCH 1/2] [X86] Stop adding liveins for virtual registers in
 emitStackProbeInlineWindowsCoreCLR64.

In the livein interface, the register goes through a MCPhysReg which
is uint16_t. This causes the virtual register bit to be dropped making
it alias to some nonsense physical register.

Found by llvm/test/CodeGen/X86/win_coreclr_chkstk.ll after replacing
the MCPhysReg with MCRegister.
---
 llvm/lib/Target/X86/X86FrameLowering.cpp | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/llvm/lib/Target/X86/X86FrameLowering.cpp b/llvm/lib/Target/X86/X86FrameLowering.cpp
index 43a3219f789c4a..39ccf22e580ade 100644
--- a/llvm/lib/Target/X86/X86FrameLowering.cpp
+++ b/llvm/lib/Target/X86/X86FrameLowering.cpp
@@ -1037,7 +1037,8 @@ void X86FrameLowering::emitStackProbeInlineWindowsCoreCLR64(
       .addImm(X86::COND_AE);
 
   // Add code to roundMBB to round the final stack pointer to a page boundary.
-  RoundMBB->addLiveIn(FinalReg);
+  if (InProlog)
+    RoundMBB->addLiveIn(FinalReg);
   BuildMI(RoundMBB, DL, TII.get(X86::AND64ri32), RoundedReg)
       .addReg(FinalReg)
       .addImm(PageMask);
@@ -1054,7 +1055,8 @@ void X86FrameLowering::emitStackProbeInlineWindowsCoreCLR64(
         .addMBB(LoopMBB);
   }
 
-  LoopMBB->addLiveIn(JoinReg);
+  if (InProlog)
+    LoopMBB->addLiveIn(JoinReg);
   addRegOffset(BuildMI(LoopMBB, DL, TII.get(X86::LEA64r), ProbeReg), JoinReg,
                false, -PageSize);
 
@@ -1067,7 +1069,8 @@ void X86FrameLowering::emitStackProbeInlineWindowsCoreCLR64(
       .addReg(0)
       .addImm(0);
 
-  LoopMBB->addLiveIn(RoundedReg);
+  if (InProlog)
+    LoopMBB->addLiveIn(RoundedReg);
   BuildMI(LoopMBB, DL, TII.get(X86::CMP64rr))
       .addReg(RoundedReg)
       .addReg(ProbeReg);
@@ -1091,7 +1094,8 @@ void X86FrameLowering::emitStackProbeInlineWindowsCoreCLR64(
 
   // Now that the probing is done, add code to continueMBB to update
   // the stack pointer for real.
-  ContinueMBB->addLiveIn(SizeReg);
+  if (InProlog)
+    ContinueMBB->addLiveIn(SizeReg);
   BuildMI(*ContinueMBB, ContinueMBBI, DL, TII.get(X86::SUB64rr), X86::RSP)
       .addReg(X86::RSP)
       .addReg(SizeReg);

>From 7c0433eae1fedcb2df5b2a2b2e32c223bed0bcce Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper at sifive.com>
Date: Fri, 30 Aug 2024 23:19:05 -0700
Subject: [PATCH 2/2] fixup! Recompute the liveins for the continue block.

---
 llvm/lib/Target/X86/X86FrameLowering.cpp    | 7 +++++--
 llvm/test/CodeGen/X86/win_coreclr_chkstk.ll | 3 +--
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/llvm/lib/Target/X86/X86FrameLowering.cpp b/llvm/lib/Target/X86/X86FrameLowering.cpp
index 39ccf22e580ade..e7c725ded4bdef 100644
--- a/llvm/lib/Target/X86/X86FrameLowering.cpp
+++ b/llvm/lib/Target/X86/X86FrameLowering.cpp
@@ -1094,8 +1094,6 @@ void X86FrameLowering::emitStackProbeInlineWindowsCoreCLR64(
 
   // Now that the probing is done, add code to continueMBB to update
   // the stack pointer for real.
-  if (InProlog)
-    ContinueMBB->addLiveIn(SizeReg);
   BuildMI(*ContinueMBB, ContinueMBBI, DL, TII.get(X86::SUB64rr), X86::RSP)
       .addReg(X86::RSP)
       .addReg(SizeReg);
@@ -1107,6 +1105,11 @@ void X86FrameLowering::emitStackProbeInlineWindowsCoreCLR64(
   LoopMBB->addSuccessor(ContinueMBB);
   LoopMBB->addSuccessor(LoopMBB);
 
+  if (InProlog) {
+    LivePhysRegs LiveRegs;
+    computeAndAddLiveIns(LiveRegs, *ContinueMBB);
+  }
+
   // Mark all the instructions added to the prolog as frame setup.
   if (InProlog) {
     for (++BeforeMBBI; BeforeMBBI != MBB.end(); ++BeforeMBBI) {
diff --git a/llvm/test/CodeGen/X86/win_coreclr_chkstk.ll b/llvm/test/CodeGen/X86/win_coreclr_chkstk.ll
index c169521ca3803c..35fc13be0f86bd 100644
--- a/llvm/test/CodeGen/X86/win_coreclr_chkstk.ll
+++ b/llvm/test/CodeGen/X86/win_coreclr_chkstk.ll
@@ -1,5 +1,4 @@
-; FIXME: Fix machine verifier issues and remove -verify-machineinstrs=0. PR38376.
-; RUN: llc < %s -mtriple=x86_64-pc-win32-coreclr -verify-machineinstrs=0 | FileCheck %s -check-prefix=WIN_X64
+; RUN: llc < %s -mtriple=x86_64-pc-win32-coreclr -verify-machineinstrs | FileCheck %s -check-prefix=WIN_X64
 ; RUN: llc < %s -mtriple=x86_64-pc-linux         | FileCheck %s -check-prefix=LINUX
 
 ; By default, windows CoreCLR requires an inline prologue stack expansion check