[LLVM][Alignment] Make functions using log of alignment explicit

Summary:
This patch renames functions that takes or returns alignment as log2, this patch will help with the transition to llvm::Align.
The renaming makes it explicit that we deal with log(alignment) instead of a power of two alignment.
A few renames uncovered dubious assignments:

 - `MirParser`/`MirPrinter` was expecting powers of two but `MachineFunction` and `MachineBasicBlock` were using deal with log2(align). This patch fixes it and updates the documentation.
 - `MachineBlockPlacement` exposes two flags (`align-all-blocks` and `align-all-nofallthru-blocks`) supposedly interpreted as power of two alignments, internally these values are interpreted as log2(align). This patch updates the documentation,
 - `MachineFunctionexposes` exposes `align-all-functions` also interpreted as power of two alignment, internally this value is interpreted as log2(align). This patch updates the documentation,

Reviewers: lattner, thegameg, courbet

Subscribers: dschuff, arsenm, jyknight, dylanmckay, sdardis, nemanjai, jvesely, nhaehnle, javed.absar, hiraditya, kbarton, fedor.sergeev, asb, rbar, johnrusso, simoncook, apazos, sabuasal, niosHD, jrtc27, MaskRay, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, dexonsmith, PkmX, jocewei, jsji, Jim, s.egerton, llvm-commits, courbet

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D65945

llvm-svn: 371045

3 files changed, 27 insertions, 26 deletions

diff --git a/llvm/include/llvm/CodeGen/MachineBasicBlock.h b/llvm/include/llvm/CodeGen/MachineBasicBlock.h
index 5bf78138f5d..e3947f4a8f1 100644
--- a/llvm/include/llvm/CodeGen/MachineBasicBlock.h
+++ b/llvm/include/llvm/CodeGen/MachineBasicBlock.h
@@ -105,7 +105,7 @@ private:
 
   /// Alignment of the basic block. Zero if the basic block does not need to be
   /// aligned. The alignment is specified as log2(bytes).
-  unsigned Alignment = 0;
+  unsigned LogAlignment = 0;
 
   /// Indicate that this basic block is entered via an exception handler.
   bool IsEHPad = false;
@@ -374,11 +374,11 @@ public:
 
   /// Return alignment of the basic block. The alignment is specified as
   /// log2(bytes).
-  unsigned getAlignment() const { return Alignment; }
+  unsigned getLogAlignment() const { return LogAlignment; }
 
   /// Set alignment of the basic block. The alignment is specified as
   /// log2(bytes).
-  void setAlignment(unsigned Align) { Alignment = Align; }
+  void setLogAlignment(unsigned A) { LogAlignment = A; }
 
   /// Returns true if the block is a landing pad. That is this basic block is
   /// entered via an exception handler.
diff --git a/llvm/include/llvm/CodeGen/MachineFunction.h b/llvm/include/llvm/CodeGen/MachineFunction.h
index c9325c746ba..b6c08f2bae7 100644
--- a/llvm/include/llvm/CodeGen/MachineFunction.h
+++ b/llvm/include/llvm/CodeGen/MachineFunction.h
@@ -277,7 +277,7 @@ class MachineFunction {
   unsigned FunctionNumber;
 
   /// Alignment - The alignment of the function.
-  unsigned Alignment;
+  unsigned LogAlignment;
 
   /// ExposesReturnsTwice - True if the function calls setjmp or related
   /// functions with attribute "returns twice", but doesn't have
@@ -508,15 +508,16 @@ public:
   const WinEHFuncInfo *getWinEHFuncInfo() const { return WinEHInfo; }
   WinEHFuncInfo *getWinEHFuncInfo() { return WinEHInfo; }
 
-  /// getAlignment - Return the alignment (log2, not bytes) of the function.
-  unsigned getAlignment() const { return Alignment; }
+  /// getLogAlignment - Return the alignment of the function.
+  unsigned getLogAlignment() const { return LogAlignment; }
 
-  /// setAlignment - Set the alignment (log2, not bytes) of the function.
-  void setAlignment(unsigned A) { Alignment = A; }
+  /// setLogAlignment - Set the alignment of the function.
+  void setLogAlignment(unsigned A) { LogAlignment = A; }
 
   /// ensureAlignment - Make sure the function is at least 1 << A bytes aligned.
-  void ensureAlignment(unsigned A) {
-    if (Alignment < A) Alignment = A;
+  void ensureLogAlignment(unsigned A) {
+    if (LogAlignment < A)
+      LogAlignment = A;
   }
 
   /// exposesReturnsTwice - Returns true if the function calls setjmp or
diff --git a/llvm/include/llvm/CodeGen/TargetLowering.h b/llvm/include/llvm/CodeGen/TargetLowering.h
index 315f209417c..de82fd71736 100644
--- a/llvm/include/llvm/CodeGen/TargetLowering.h
+++ b/llvm/include/llvm/CodeGen/TargetLowering.h
@@ -1582,18 +1582,18 @@ public:
   }
 
   /// Return the minimum function alignment.
-  unsigned getMinFunctionAlignment() const {
-    return MinFunctionAlignment;
+  unsigned getMinFunctionLogAlignment() const {
+    return MinFunctionLogAlignment;
   }
 
   /// Return the preferred function alignment.
-  unsigned getPrefFunctionAlignment() const {
-    return PrefFunctionAlignment;
+  unsigned getPrefFunctionLogAlignment() const {
+    return PrefFunctionLogAlignment;
   }
 
   /// Return the preferred loop alignment.
-  virtual unsigned getPrefLoopAlignment(MachineLoop *ML = nullptr) const {
-    return PrefLoopAlignment;
+  virtual unsigned getPrefLoopLogAlignment(MachineLoop *ML = nullptr) const {
+    return PrefLoopLogAlignment;
   }
 
   /// Should loops be aligned even when the function is marked OptSize (but not
@@ -2105,23 +2105,23 @@ protected:
   }
 
   /// Set the target's minimum function alignment (in log2(bytes))
-  void setMinFunctionAlignment(unsigned Align) {
-    MinFunctionAlignment = Align;
+  void setMinFunctionLogAlignment(unsigned LogAlign) {
+    MinFunctionLogAlignment = LogAlign;
   }
 
   /// Set the target's preferred function alignment.  This should be set if
   /// there is a performance benefit to higher-than-minimum alignment (in
   /// log2(bytes))
-  void setPrefFunctionAlignment(unsigned Align) {
-    PrefFunctionAlignment = Align;
+  void setPrefFunctionLogAlignment(unsigned LogAlign) {
+    PrefFunctionLogAlignment = LogAlign;
   }
 
   /// Set the target's preferred loop alignment. Default alignment is zero, it
   /// means the target does not care about loop alignment.  The alignment is
   /// specified in log2(bytes). The target may also override
   /// getPrefLoopAlignment to provide per-loop values.
-  void setPrefLoopAlignment(unsigned Align) {
-    PrefLoopAlignment = Align;
+  void setPrefLoopLogAlignment(unsigned LogAlign) {
+    PrefLoopLogAlignment = LogAlign;
   }
 
   /// Set the minimum stack alignment of an argument (in log2(bytes)).
@@ -2692,14 +2692,14 @@ private:
 
   /// The minimum function alignment (used when optimizing for size, and to
   /// prevent explicitly provided alignment from leading to incorrect code).
-  unsigned MinFunctionAlignment;
+  unsigned MinFunctionLogAlignment;
 
   /// The preferred function alignment (used when alignment unspecified and
   /// optimizing for speed).
-  unsigned PrefFunctionAlignment;
+  unsigned PrefFunctionLogAlignment;
 
-  /// The preferred loop alignment.
-  unsigned PrefLoopAlignment;
+  /// The preferred loop alignment (in log2 bot in bytes).
+  unsigned PrefLoopLogAlignment;
 
   /// Size in bits of the maximum atomics size the backend supports.
   /// Accesses larger than this will be expanded by AtomicExpandPass.