[llvm] 9fe7aef - [CodeGen] Don't check attrs for stack realign (#92564)

[via llvm-commits]

Author: aengelke
Date: 2024-05-29T20:38:34+02:00
New Revision: 9fe7aef1889300a17a594efb55358ebd032a81a2

URL: https://github.com/llvm/llvm-project/commit/9fe7aef1889300a17a594efb55358ebd032a81a2
DIFF: https://github.com/llvm/llvm-project/commit/9fe7aef1889300a17a594efb55358ebd032a81a2.diff

LOG: [CodeGen] Don't check attrs for stack realign (#92564)

shouldRealignStack/canRealignStack are repeatedly called in PEI (through
hasStackRealignment). Checking function attributes is expensive, so
cache this data in the MachineFrameInfo, which had most data already.

This slightly changes the semantics of `MachineFrameInfo::ForcedRealign`
to be also true when the `stackrealign` attribute is set.

Added: 
    

Modified: 
    llvm/include/llvm/CodeGen/MachineFrameInfo.h
    llvm/lib/CodeGen/MachineFunction.cpp
    llvm/lib/CodeGen/TargetRegisterInfo.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/CodeGen/MachineFrameInfo.h b/llvm/include/llvm/CodeGen/MachineFrameInfo.h
index a2c78e9e093d0..466fed7fb3a29 100644
--- a/llvm/include/llvm/CodeGen/MachineFrameInfo.h
+++ b/llvm/include/llvm/CodeGen/MachineFrameInfo.h
@@ -346,6 +346,8 @@ class MachineFrameInfo {
 
   MachineFrameInfo(const MachineFrameInfo &) = delete;
 
+  bool isStackRealignable() const { return StackRealignable; }
+
   /// Return true if there are any stack objects in this function.
   bool hasStackObjects() const { return !Objects.empty(); }
 
@@ -603,6 +605,12 @@ class MachineFrameInfo {
   /// Make sure the function is at least Align bytes aligned.
   void ensureMaxAlignment(Align Alignment);
 
+  /// Return true if stack realignment is forced by function attributes or if
+  /// the stack alignment.
+  bool shouldRealignStack() const {
+    return ForcedRealign || MaxAlignment > StackAlignment;
+  }
+
   /// Return true if this function adjusts the stack -- e.g.,
   /// when calling another function. This is only valid during and after
   /// prolog/epilog code insertion.

diff  --git a/llvm/lib/CodeGen/MachineFunction.cpp b/llvm/lib/CodeGen/MachineFunction.cpp
index 8366ad2859069..4182e75354125 100644
--- a/llvm/lib/CodeGen/MachineFunction.cpp
+++ b/llvm/lib/CodeGen/MachineFunction.cpp
@@ -200,10 +200,11 @@ void MachineFunction::init() {
   // explicitly asked us not to.
   bool CanRealignSP = STI->getFrameLowering()->isStackRealignable() &&
                       !F.hasFnAttribute("no-realign-stack");
+  bool ForceRealignSP = F.hasFnAttribute(Attribute::StackAlignment) ||
+                        F.hasFnAttribute("stackrealign");
   FrameInfo = new (Allocator) MachineFrameInfo(
       getFnStackAlignment(STI, F), /*StackRealignable=*/CanRealignSP,
-      /*ForcedRealign=*/CanRealignSP &&
-          F.hasFnAttribute(Attribute::StackAlignment));
+      /*ForcedRealign=*/ForceRealignSP && CanRealignSP);
 
   setUnsafeStackSize(F, *FrameInfo);
 

diff  --git a/llvm/lib/CodeGen/TargetRegisterInfo.cpp b/llvm/lib/CodeGen/TargetRegisterInfo.cpp
index 4e06393f4cc1d..ffc8055dd27e8 100644
--- a/llvm/lib/CodeGen/TargetRegisterInfo.cpp
+++ b/llvm/lib/CodeGen/TargetRegisterInfo.cpp
@@ -474,16 +474,11 @@ bool TargetRegisterInfo::isCalleeSavedPhysReg(
 }
 
 bool TargetRegisterInfo::canRealignStack(const MachineFunction &MF) const {
-  return !MF.getFunction().hasFnAttribute("no-realign-stack");
+  return MF.getFrameInfo().isStackRealignable();
 }
 
 bool TargetRegisterInfo::shouldRealignStack(const MachineFunction &MF) const {
-  const MachineFrameInfo &MFI = MF.getFrameInfo();
-  const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
-  const Function &F = MF.getFunction();
-  return F.hasFnAttribute("stackrealign") ||
-         (MFI.getMaxAlign() > TFI->getStackAlign()) ||
-         F.hasFnAttribute(Attribute::StackAlignment);
+  return MF.getFrameInfo().shouldRealignStack();
 }
 
 bool TargetRegisterInfo::regmaskSubsetEqual(const uint32_t *mask0,