[llvm] Only check assertions that were meant to apply to the normal case of non-splat vector SREM expansion when we aren't hitting the special case. (PR #86238)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-selectiondag

Author: Owen Anderson (resistor)

<details>
<summary>Changes</summary>

Fixes https://github.com/llvm/llvm-project/issues/84830
Introduced in https://github.com/llvm/llvm-project/pull/82706


---
Full diff: https://github.com/llvm/llvm-project/pull/86238.diff


2 Files Affected:

- (modified) llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp (+5-5) 
- (added) llvm/test/CodeGen/AArch64/srem-vec-crash.ll (+14) 


``````````diff
diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index da29b1d5b312f8..8be03b66e155f6 100644
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -6916,6 +6916,11 @@ TargetLowering::prepareSREMEqFold(EVT SETCCVT, SDValue REMNode,
     // Q = floor((2 * A) / (2^K))
     APInt Q = (2 * A).udiv(APInt::getOneBitSet(W, K));
 
+    assert(APInt::getAllOnes(SVT.getSizeInBits()).ugt(A) &&
+           "We are expecting that A is always less than all-ones for SVT");
+    assert(APInt::getAllOnes(ShSVT.getSizeInBits()).ugt(K) &&
+           "We are expecting that K is always less than all-ones for ShSVT");
+
     // If D was a power of two, apply the alternate constant derivation.
     if (D0.isOne()) {
       // A = 2^(W-1)
@@ -6924,11 +6929,6 @@ TargetLowering::prepareSREMEqFold(EVT SETCCVT, SDValue REMNode,
       Q = APInt::getAllOnes(W - K).zext(W);
     }
 
-    assert(APInt::getAllOnes(SVT.getSizeInBits()).ugt(A) &&
-           "We are expecting that A is always less than all-ones for SVT");
-    assert(APInt::getAllOnes(ShSVT.getSizeInBits()).ugt(K) &&
-           "We are expecting that K is always less than all-ones for ShSVT");
-
     // If the divisor is 1 the result can be constant-folded. Likewise, we
     // don't care about INT_MIN lanes, those can be set to undef if appropriate.
     if (D.isOne()) {
diff --git a/llvm/test/CodeGen/AArch64/srem-vec-crash.ll b/llvm/test/CodeGen/AArch64/srem-vec-crash.ll
new file mode 100644
index 00000000000000..3b8a1c83b2f697
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/srem-vec-crash.ll
@@ -0,0 +1,14 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 4
+;RUN: llc -mtriple=aarch64-unknown-unknown < %s | FileCheck %s
+
+define i32 @f(i1 %0) {
+; CHECK-LABEL: f:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    mov w0, #1 // =0x1
+; CHECK-NEXT:    ret
+  %new0 = srem i1 %0, true
+  %last = zext i1 %new0 to i32
+  %2 = icmp ne i32 %last, 0
+  %3 = select i1 %2, i32 0, i32 1
+  ret i32 %3
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/86238