Teach InstructionSimplify about phi nodes. I chose to have it simply

offload the work to hasConstantValue rather than do something more
complicated (such handling mutually recursive phis) because (1) it is
not clear it is worth it; and (2) if it is worth it, maybe such logic
would be better placed in hasConstantValue.  Adjust some GVN tests
which are now cleaned up much further (eg: all phi nodes are removed).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119043 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index b3e817a750623641ce12e182ce4a7a61f04e497a..210399d7291ebb1b3b592eac1d9e3cc9e75c2ec6 100644 (file)
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -699,6 +699,8 @@ Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD) {
     SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
     return SimplifyGEPInst(&Ops[0], Ops.size(), TD);
   }
+  case Instruction::PHI:
+    return cast<PHINode>(I)->hasConstantValue();
   }
 }
 

diff --git a/lib/Transforms/InstCombine/InstCombinePHI.cpp b/lib/Transforms/InstCombine/InstCombinePHI.cpp
index f7fc62f9dc4fca89ae64d22ee1921edfce16988a..736473db1d584699d4ffd262a6887b5dc49f7e5e 100644 (file)
--- a/lib/Transforms/InstCombine/InstCombinePHI.cpp
+++ b/lib/Transforms/InstCombine/InstCombinePHI.cpp
@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "InstCombine.h"
+#include "llvm/Analysis/InstructionSimplify.h"
 #include "llvm/Target/TargetData.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/STLExtras.h"
@@ -731,8 +732,8 @@ Instruction *InstCombiner::SliceUpIllegalIntegerPHI(PHINode &FirstPhi) {
 Instruction *InstCombiner::visitPHINode(PHINode &PN) {
   // If LCSSA is around, don't mess with Phi nodes
   if (MustPreserveLCSSA) return 0;
-  
-  if (Value *V = PN.hasConstantValue())
+
+  if (Value *V = SimplifyInstruction(&PN, TD))
     return ReplaceInstUsesWith(PN, V);
 
   // If all PHI operands are the same operation, pull them through the PHI,

diff --git a/test/Transforms/GVN/2007-07-26-InterlockingLoops.ll b/test/Transforms/GVN/2007-07-26-InterlockingLoops.ll
index 13d1bd1b7ef0dd1b006cbe4cbc7096086de7c681..14cb91b5316728ac8ea529c45d0964a4c2199ffa 100644 (file)
--- a/test/Transforms/GVN/2007-07-26-InterlockingLoops.ll
+++ b/test/Transforms/GVN/2007-07-26-InterlockingLoops.ll
@@ -1,30 +1,33 @@
-; RUN: opt < %s -basicaa -gvn -S | grep {tmp17625.* = phi i32. }
-; RUN: opt < %s -basicaa -gvn -S | grep {tmp17631.* = phi i32. }
+; RUN: opt < %s -basicaa -gvn -S | FileCheck %s
 
-@last = external global [65 x i32*]            ; <[65 x i32*]*> [#uses=1]
+@last = external global [65 x i32*]
 
 define i32 @NextRootMove(i32 %wtm) {
-cond_next95:           ; preds = %cond_true85, %cond_true79, %cond_true73, %bb68
-       %tmp17618 = load i32** getelementptr ([65 x i32*]* @last, i32 0, i32 1), align 4                ; <i32*> [#uses=0]
+entry:
+       %tmp17618 = load i32** getelementptr ([65 x i32*]* @last, i32 0, i32 1), align 4
+; CHECK: entry:
+; CHECK-NEXT: %tmp17618 = load
+; CHECK-NOT: load
+; CHECK-NOT: phi
        br label %cond_true116
 
-cond_true116:          ; preds = %cond_true111
+cond_true116:
        br i1 false, label %cond_true128, label %cond_true145
 
-cond_true128:          ; preds = %cond_true121
-       %tmp17625 = load i32** getelementptr ([65 x i32*]* @last, i32 0, i32 1), align 4                ; <i32*> [#uses=0]
+cond_true128:
+       %tmp17625 = load i32** getelementptr ([65 x i32*]* @last, i32 0, i32 1), align 4
        br i1 false, label %bb98.backedge, label %return.loopexit
 
-bb98.backedge:         ; preds = %bb171, %cond_true145, %cond_true128
+bb98.backedge:
        br label %cond_true116
 
-cond_true145:          ; preds = %cond_false
-       %tmp17631 = load i32** getelementptr ([65 x i32*]* @last, i32 0, i32 1), align 4                ; <i32*> [#uses=0]
+cond_true145:
+       %tmp17631 = load i32** getelementptr ([65 x i32*]* @last, i32 0, i32 1), align 4
        br i1 false, label %bb98.backedge, label %return.loopexit
 
-return.loopexit:               ; preds = %bb171, %cond_true145, %cond_true128
+return.loopexit:
        br label %return
 
-return:                ; preds = %return.loopexit, %cond_next95, %cond_true85
+return:
        ret i32 0
 }

diff --git a/test/Transforms/GVN/2010-03-31-RedundantPHIs.ll b/test/Transforms/GVN/2010-03-31-RedundantPHIs.ll
index c408daa58da17f7a37c28b08b26536c76004a302..d6e1c6b76d0b3d709e61ad44569341832657f27f 100644 (file)
--- a/test/Transforms/GVN/2010-03-31-RedundantPHIs.ll
+++ b/test/Transforms/GVN/2010-03-31-RedundantPHIs.ll
@@ -1,5 +1,8 @@
 ; RUN: opt < %s -basicaa -gvn -S | FileCheck %s
 
+; CHECK-NOT: load
+; CHECK-NOT: phi
+
 define i8* @cat(i8* %s1, ...) nounwind {
 entry:
   br i1 undef, label %bb, label %bb3
@@ -29,18 +32,11 @@ bb10:                                             ; preds = %bb8
   br label %bb11
 
 bb11:                                             ; preds = %bb10, %bb9
-; CHECK: bb11:
-; CHECK: phi
-; CHECK-NOT: phi
   br label %bb12
 
 bb12:                                             ; preds = %bb11, %bb6
-; CHECK: bb12:
-; CHECK: phi
-; CHECK-NOT: phi
   br i1 undef, label %bb8, label %bb13
 
 bb13:                                             ; preds = %bb12
-; CHECK: bb13:
   ret i8* undef
 }