[llvm] 6ef9a2a - [LICM] Use poison to replace unreachable values instead of undef [NFC]

[Nuno Lopes via llvm-commits]

Author: Nuno Lopes
Date: 2022-06-26T14:56:35+01:00
New Revision: 6ef9a2ad01c07072352ce228e41b2aa44483d421

URL: https://github.com/llvm/llvm-project/commit/6ef9a2ad01c07072352ce228e41b2aa44483d421
DIFF: https://github.com/llvm/llvm-project/commit/6ef9a2ad01c07072352ce228e41b2aa44483d421.diff

LOG: [LICM] Use poison to replace unreachable values instead of undef [NFC]

Added: 
    

Modified: 
    llvm/lib/Transforms/Scalar/LICM.cpp
    llvm/test/Transforms/LICM/PR19798.ll
    llvm/test/Transforms/LICM/PR24013.ll
    llvm/test/Transforms/LICM/pr35342.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Scalar/LICM.cpp b/llvm/lib/Transforms/Scalar/LICM.cpp
index 2cb59509af7fc..492f4e40395a1 100644
--- a/llvm/lib/Transforms/Scalar/LICM.cpp
+++ b/llvm/lib/Transforms/Scalar/LICM.cpp
@@ -1606,7 +1606,7 @@ static bool sink(Instruction &I, LoopInfo *LI, DominatorTree *DT,
       continue;
 
     if (!DT->isReachableFromEntry(User->getParent())) {
-      U = UndefValue::get(I.getType());
+      U = PoisonValue::get(I.getType());
       Changed = true;
       continue;
     }
@@ -1619,7 +1619,7 @@ static bool sink(Instruction &I, LoopInfo *LI, DominatorTree *DT,
     // unreachable.
     BasicBlock *BB = PN->getIncomingBlock(U);
     if (!DT->isReachableFromEntry(BB)) {
-      U = UndefValue::get(I.getType());
+      U = PoisonValue::get(I.getType());
       Changed = true;
       continue;
     }

diff  --git a/llvm/test/Transforms/LICM/PR19798.ll b/llvm/test/Transforms/LICM/PR19798.ll
index 82befb09666ca..4670f0e375342 100644
--- a/llvm/test/Transforms/LICM/PR19798.ll
+++ b/llvm/test/Transforms/LICM/PR19798.ll
@@ -1,20 +1,20 @@
 ; RUN: opt -licm -S < %s | FileCheck %s
 
-define void @f() {
+define void @f(i1 %c) {
 ; CHECK-LABEL: @f(
 entry:
   br label %bb0
 
 bb0:
-  %tobool7 = icmp eq i1 undef, undef
+  %tobool7 = icmp eq i1 0, 1
   br label %bb1
 
 bb1:
-  br i1 undef, label %bb0, label %bb0
+  br i1 %c, label %bb0, label %bb0
 
 unreachable:
 ; CHECK-LABEL: unreachable:
-; CHECK:   br i1 undef, label %unreachable, label %unreachable
+; CHECK:   br i1 poison, label %unreachable, label %unreachable
   br i1 %tobool7, label %unreachable, label %unreachable
 
 bb3:

diff  --git a/llvm/test/Transforms/LICM/PR24013.ll b/llvm/test/Transforms/LICM/PR24013.ll
index 4557bfcfd1226..7f8489e5a0de4 100644
--- a/llvm/test/Transforms/LICM/PR24013.ll
+++ b/llvm/test/Transforms/LICM/PR24013.ll
@@ -9,11 +9,11 @@ lbl.loopexit:                                     ; No predecessors!
   br label %lbl
 
 lbl:                                              ; preds = %lbl.loopexit, %entry
-  %phi = phi i32 [ %conv, %lbl.loopexit ], [ undef, %entry ]
-; CHECK: phi i32 [ undef, {{.*}} ], [ undef
+  %phi = phi i32 [ %conv, %lbl.loopexit ], [ poison, %entry ]
+; CHECK: phi i32 [ poison, {{.*}} ], [ poison
   br label %if.then.5
 
 if.then.5:                                        ; preds = %if.then.5, %lbl
-  %conv = zext i1 undef to i32
+  %conv = zext i1 0 to i32
   br label %if.then.5
 }

diff  --git a/llvm/test/Transforms/LICM/pr35342.ll b/llvm/test/Transforms/LICM/pr35342.ll
index d6af208e2f2d8..481118357e32b 100644
--- a/llvm/test/Transforms/LICM/pr35342.ll
+++ b/llvm/test/Transforms/LICM/pr35342.ll
@@ -5,16 +5,16 @@ target triple = "x86_64-unknown-linux-gnu"
 
 ; CHECK-LABEL: @f1
 ; CHECK-LABEL: bci_524:
-; CHECK: add i32 undef, undef
-define void @f1(i32 %v) {
+; CHECK: add i32 poison, poison
+define void @f1(i32 %v, i1 %c) {
 not_zero.lr.ph:
   br label %not_zero
 
 not_zero:
-  br i1 undef, label %bci_748 ,  label %bci_314
+  br i1 %c, label %bci_748 ,  label %bci_314
 
 bci_314:
-  %0 = select i1 undef, i32 undef, i32 undef
+  %0 = select i1 poison, i32 poison, i32 poison
   br label %not_zero
 
 bci_524:                   ; No predecessors!