[llvm] 5a069ea - [AArch64] Don't try to sink and(load) (#122274)

[via llvm-commits]

Author: David Green
Date: 2025-01-10T11:54:46Z
New Revision: 5a069eac5fbb7752e7602b783ee0102e8269c47a

URL: https://github.com/llvm/llvm-project/commit/5a069eac5fbb7752e7602b783ee0102e8269c47a
DIFF: https://github.com/llvm/llvm-project/commit/5a069eac5fbb7752e7602b783ee0102e8269c47a.diff

LOG: [AArch64] Don't try to sink and(load) (#122274)

If we sink the and in and(load), CGP can hoist is back again to the
load, getting into an infinite loop. This prevents sinking the and in
this case.

Fixes #122074

Added: 
    

Modified: 
    llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
    llvm/test/CodeGen/AArch64/aarch64-dup-ext-crash.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
index 29ea098386cec1..932a6f9ce23fd2 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
@@ -5514,7 +5514,10 @@ bool AArch64TTIImpl::isProfitableToSinkOperands(
         NumZExts++;
       }
 
-      Ops.push_back(&Insert->getOperandUse(1));
+      // And(Load) is excluded to prevent CGP getting stuck in a loop of sinking
+      // the And, just to hoist it again back to the load.
+      if (!match(OperandInstr, m_And(m_Load(m_Value()), m_Value())))
+        Ops.push_back(&Insert->getOperandUse(1));
       Ops.push_back(&Shuffle->getOperandUse(0));
       Ops.push_back(&Op);
     }

diff  --git a/llvm/test/CodeGen/AArch64/aarch64-dup-ext-crash.ll b/llvm/test/CodeGen/AArch64/aarch64-dup-ext-crash.ll
index 95c54cd8b01511..478c1be8821f6c 100644
--- a/llvm/test/CodeGen/AArch64/aarch64-dup-ext-crash.ll
+++ b/llvm/test/CodeGen/AArch64/aarch64-dup-ext-crash.ll
@@ -9,7 +9,7 @@ target triple = "aarch64-unknown-linux-gnu"
 ; here, only that this case no longer causes said crash.
 define dso_local i32 @dupext_crashtest(i32 %e) local_unnamed_addr {
 ; CHECK-LABEL: dupext_crashtest:
-; CHECK:       // %bb.0: // %for.body.lr.ph
+; CHECK:       // %bb.0: // %entry
 ; CHECK-NEXT:    dup v0.2s, w0
 ; CHECK-NEXT:  .LBB0_1: // %vector.body
 ; CHECK-NEXT:    // =>This Inner Loop Header: Depth=1
@@ -18,7 +18,7 @@ define dso_local i32 @dupext_crashtest(i32 %e) local_unnamed_addr {
 ; CHECK-NEXT:    xtn v1.2s, v1.2d
 ; CHECK-NEXT:    str d1, [x8]
 ; CHECK-NEXT:    b .LBB0_1
-for.body.lr.ph:
+entry:
   %conv314 = zext i32 %e to i64
   br label %vector.memcheck
 
@@ -40,3 +40,49 @@ vector.body:                                      ; preds = %vector.body, %vecto
   store <2 x i32> %3, ptr %4, align 4
   br label %vector.body
 }
+
+; This test got stuck in a loop hoisting the and to the load, and sinking it back to the mull
+define i32 @dup_and_load(ptr %p, i1 %c) {
+; CHECK-LABEL: dup_and_load:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    mov x8, x0
+; CHECK-NEXT:    ldrb w0, [x0]
+; CHECK-NEXT:    tbz w1, #0, .LBB1_3
+; CHECK-NEXT:  // %bb.1: // %ph
+; CHECK-NEXT:    dup v0.8h, w0
+; CHECK-NEXT:    mov w9, wzr
+; CHECK-NEXT:  .LBB1_2: // %vector.body
+; CHECK-NEXT:    // =>This Inner Loop Header: Depth=1
+; CHECK-NEXT:    ldr d1, [x8]
+; CHECK-NEXT:    add w9, w9, #1
+; CHECK-NEXT:    cmp w9, #100
+; CHECK-NEXT:    ushll v1.8h, v1.8b, #0
+; CHECK-NEXT:    umull2 v2.4s, v0.8h, v1.8h
+; CHECK-NEXT:    umull v1.4s, v0.4h, v1.4h
+; CHECK-NEXT:    stp q1, q2, [x8]
+; CHECK-NEXT:    b.lt .LBB1_2
+; CHECK-NEXT:  .LBB1_3: // %end
+; CHECK-NEXT:    ret
+entry:
+  %l = load i32, ptr %p
+  %and255 = and i32 %l, 255
+  br i1 %c, label %ph, label %end
+
+ph:
+  %broadcast.splatinsert = insertelement <8 x i32> poison, i32 %and255, i32 0
+  %broadcast.splat = shufflevector <8 x i32> %broadcast.splatinsert, <8 x i32> poison, <8 x i32> zeroinitializer
+  br label %vector.body
+
+vector.body:                                      ; preds = %vector.body, %vector.ph
+  %iv = phi i32 [ 0, %ph ], [ %iv.next, %vector.body ]
+  %wide.load = load <8 x i8>, ptr %p, align 4
+  %0 = zext <8 x i8> %wide.load to <8 x i32>
+  %1 = mul <8 x i32> %broadcast.splat, %0
+  store <8 x i32> %1, ptr %p, align 4
+  %iv.next = add i32 %iv, 1
+  %e = icmp slt i32 %iv.next, 100
+  br i1 %e, label %vector.body, label %end
+
+end:
+  ret i32 %and255
+}