[llvm] goldsteinn/cgp urem of liv (PR #96625)
via llvm-commits
llvm-commits at lists.llvm.org
Tue Jun 25 05:09:34 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-backend-x86
Author: None (goldsteinn)
<details>
<summary>Changes</summary>
- **[CodeGenPrepare][X86] Add tests for folding `urem` with loop invariant value; NFC**
- **[CodeGenPrepare] Folding `urem` with loop invariant value**
---
Patch is 34.16 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/96625.diff
2 Files Affected:
- (modified) llvm/lib/CodeGen/CodeGenPrepare.cpp (+157)
- (added) llvm/test/CodeGen/X86/fold-loop-of-urem.ll (+864)
``````````diff
diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index 900c33b580f15..d2cc3b4cb326c 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -471,6 +471,7 @@ class CodeGenPrepare {
bool replaceMathCmpWithIntrinsic(BinaryOperator *BO, Value *Arg0, Value *Arg1,
CmpInst *Cmp, Intrinsic::ID IID);
bool optimizeCmp(CmpInst *Cmp, ModifyDT &ModifiedDT);
+ bool optimizeRem(Instruction *Rem);
bool combineToUSubWithOverflow(CmpInst *Cmp, ModifyDT &ModifiedDT);
bool combineToUAddWithOverflow(CmpInst *Cmp, ModifyDT &ModifiedDT);
void verifyBFIUpdates(Function &F);
@@ -1974,6 +1975,157 @@ static bool foldFCmpToFPClassTest(CmpInst *Cmp, const TargetLowering &TLI,
return true;
}
+static bool isRemOfLoopIncrementWithLIV(Value *Rem, const LoopInfo *LI,
+ Value *&RemAmtOut,
+ std::optional<bool> &AddOrSubOut,
+ Value *&AddOrSubOffsetOut,
+ PHINode *&LoopIncrPNOut) {
+ Value *Incr, *RemAmt;
+ if (!isa<Instruction>(Rem))
+ return false;
+ // NB: If RemAmt is a power of 2 it *should* have been transformed by now.
+ if (!match(Rem, m_URem(m_Value(Incr), m_Value(RemAmt))))
+ return false;
+
+ // Only trivially analyzable loops.
+ Loop *L = LI->getLoopFor(cast<Instruction>(Rem)->getParent());
+ if (L == nullptr || L->getLoopPreheader() == nullptr ||
+ L->getLoopLatch() == nullptr)
+ return false;
+
+ std::optional<bool> AddOrSub;
+ Value *AddOrSubOffset;
+ // Find out loop increment PHI.
+ PHINode *PN = dyn_cast<PHINode>(Incr);
+ if (PN != nullptr) {
+ AddOrSub = std::nullopt;
+ AddOrSubOffset = nullptr;
+ } else {
+ // Search through a NUW add/sub.
+ Value *V0, *V1;
+ if (match(Incr, m_NUWAddLike(m_Value(V0), m_Value(V1))))
+ AddOrSub = true;
+ else if (match(Incr, m_NUWSub(m_Value(V0), m_Value(V1))))
+ AddOrSub = false;
+ else
+ return false;
+
+ PN = dyn_cast<PHINode>(V0);
+ if (PN != nullptr) {
+ AddOrSubOffset = V1;
+ } else if (*AddOrSub) {
+ PN = dyn_cast<PHINode>(V1);
+ AddOrSubOffset = V0;
+ }
+ }
+
+ if (PN == nullptr)
+ return false;
+
+ // This isn't strictly necessary, what we really need is one increment and any
+ // amount of initial values all being the same.
+ if (PN->getNumIncomingValues() != 2)
+ return false;
+
+ // Only works if the remainder amount is a loop invaraint
+ if (!L->isLoopInvariant(RemAmt))
+ return false;
+
+ // Is the PHI a loop increment?
+ auto LoopIncrInfo = getIVIncrement(PN, LI);
+ if (!LoopIncrInfo.has_value())
+ return false;
+
+ // We need remainder_amount % increment_amount to be zero. Increment of one
+ // satisfies that without any special logic and is overwhelmingly the common
+ // case.
+ if (!match(LoopIncrInfo->second, m_One()))
+ return false;
+
+ // Need the increment to not overflow.
+ if (!match(LoopIncrInfo->first, m_NUWAdd(m_Value(), m_Value())))
+ return false;
+
+ // Set output variables.
+ RemAmtOut = RemAmt;
+ LoopIncrPNOut = PN;
+ AddOrSubOut = AddOrSub;
+ AddOrSubOffsetOut = AddOrSubOffset;
+
+ return true;
+}
+
+// Try to transform:
+//
+// for(i = Start; i < End; ++i)
+// Rem = (i nuw+ IncrLoopInvariant) u% RemAmtLoopInvariant;
+//
+// ->
+//
+// Rem = (Start nuw+ IncrLoopInvariant) % RemAmtLoopInvariant;
+// for(i = Start; i < End; ++i, ++rem)
+// Rem = rem == RemAmtLoopInvariant ? 0 : Rem;
+//
+// Currently only implemented for `Start` and `IncrLoopInvariant` being zero.
+static bool foldURemOfLoopIncrement(Instruction *Rem, const LoopInfo *LI,
+ SmallSet<BasicBlock *, 32> &FreshBBs,
+ bool IsHuge) {
+ std::optional<bool> AddOrSub;
+ Value *AddOrSubOffset, *RemAmt;
+ PHINode *LoopIncrPN;
+ if (!isRemOfLoopIncrementWithLIV(Rem, LI, RemAmt, AddOrSub, AddOrSubOffset,
+ LoopIncrPN))
+ return false;
+
+ // Only non-constant remainder as the extra IV is is probably not profitable
+ // in that case. Further, since remainder amount is non-constant, only handle
+ // case where `IncrLoopInvariant` and `Start` are 0 to entirely eliminate the
+ // rem (as opposed to just hoisting it outside of the loop).
+ //
+ // Potential TODO: Should we have a check for how "nested" this remainder
+ // operation is? The new code runs every iteration so if the remainder is
+ // guarded behind unlikely conditions this might not be worth it.
+ if (AddOrSub.has_value() || match(RemAmt, m_ImmConstant()))
+ return false;
+ Loop *L = LI->getLoopFor(Rem->getParent());
+ if (!match(LoopIncrPN->getIncomingValueForBlock(L->getLoopPreheader()),
+ m_Zero()))
+ return false;
+
+ // Create new remainder with induction variable.
+ Type *Ty = Rem->getType();
+ IRBuilder<> Builder(Rem->getContext());
+
+ Builder.SetInsertPoint(LoopIncrPN);
+ PHINode *NewRem = Builder.CreatePHI(Ty, 2);
+
+ Builder.SetInsertPoint(cast<Instruction>(
+ LoopIncrPN->getIncomingValueForBlock(L->getLoopLatch())));
+ // `(add (urem x, y), 1)` is always nuw.
+ Value *RemAdd = Builder.CreateNUWAdd(NewRem, ConstantInt::get(Ty, 1));
+ Value *RemCmp = Builder.CreateICmp(ICmpInst::ICMP_EQ, RemAdd, RemAmt);
+ Value *RemSel =
+ Builder.CreateSelect(RemCmp, Constant::getNullValue(Ty), RemAdd);
+
+ NewRem->addIncoming(Constant::getNullValue(Ty), L->getLoopPreheader());
+ NewRem->addIncoming(RemSel, L->getLoopLatch());
+
+ // Insert all touched BBs.
+ FreshBBs.insert(LoopIncrPN->getParent());
+ FreshBBs.insert(L->getLoopLatch());
+ FreshBBs.insert(Rem->getParent());
+
+ replaceAllUsesWith(Rem, NewRem, FreshBBs, IsHuge);
+ Rem->eraseFromParent();
+ return true;
+}
+
+bool CodeGenPrepare::optimizeRem(Instruction *Rem) {
+ if (foldURemOfLoopIncrement(Rem, LI, FreshBBs, IsHugeFunc))
+ return true;
+ return false;
+}
+
bool CodeGenPrepare::optimizeCmp(CmpInst *Cmp, ModifyDT &ModifiedDT) {
if (sinkCmpExpression(Cmp, *TLI))
return true;
@@ -8360,6 +8512,11 @@ bool CodeGenPrepare::optimizeInst(Instruction *I, ModifyDT &ModifiedDT) {
if (optimizeCmp(Cmp, ModifiedDT))
return true;
+ if (match(I, m_URem(m_Value(), m_Value())) ||
+ match(I, m_SRem(m_Value(), m_Value())))
+ if (optimizeRem(I))
+ return true;
+
if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
LI->setMetadata(LLVMContext::MD_invariant_group, nullptr);
bool Modified = optimizeLoadExt(LI);
diff --git a/llvm/test/CodeGen/X86/fold-loop-of-urem.ll b/llvm/test/CodeGen/X86/fold-loop-of-urem.ll
new file mode 100644
index 0000000000000..9b093ec259201
--- /dev/null
+++ b/llvm/test/CodeGen/X86/fold-loop-of-urem.ll
@@ -0,0 +1,864 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown | FileCheck %s
+
+declare void @use.i32(i32)
+declare void @use.2xi64(<2 x i64>)
+declare void @do_stuff0()
+declare void @do_stuff1()
+declare i1 @get.i1()
+declare i32 @get.i32()
+
+define void @simple_urem_to_sel(i32 %N, i32 %rem_amt) nounwind {
+; CHECK-LABEL: simple_urem_to_sel:
+; CHECK: # %bb.0: # %entry
+; CHECK-NEXT: testl %edi, %edi
+; CHECK-NEXT: je .LBB0_4
+; CHECK-NEXT: # %bb.1: # %for.body.preheader
+; CHECK-NEXT: pushq %rbp
+; CHECK-NEXT: pushq %r15
+; CHECK-NEXT: pushq %r14
+; CHECK-NEXT: pushq %r12
+; CHECK-NEXT: pushq %rbx
+; CHECK-NEXT: movl %esi, %ebx
+; CHECK-NEXT: movl %edi, %ebp
+; CHECK-NEXT: xorl %r15d, %r15d
+; CHECK-NEXT: xorl %r14d, %r14d
+; CHECK-NEXT: xorl %r12d, %r12d
+; CHECK-NEXT: .p2align 4, 0x90
+; CHECK-NEXT: .LBB0_2: # %for.body
+; CHECK-NEXT: # =>This Inner Loop Header: Depth=1
+; CHECK-NEXT: movl %r14d, %edi
+; CHECK-NEXT: callq use.i32 at PLT
+; CHECK-NEXT: incl %r14d
+; CHECK-NEXT: cmpl %ebx, %r14d
+; CHECK-NEXT: cmovel %r15d, %r14d
+; CHECK-NEXT: incl %r12d
+; CHECK-NEXT: cmpl %r12d, %ebp
+; CHECK-NEXT: jne .LBB0_2
+; CHECK-NEXT: # %bb.3:
+; CHECK-NEXT: popq %rbx
+; CHECK-NEXT: popq %r12
+; CHECK-NEXT: popq %r14
+; CHECK-NEXT: popq %r15
+; CHECK-NEXT: popq %rbp
+; CHECK-NEXT: .LBB0_4: # %for.cond.cleanup
+; CHECK-NEXT: retq
+entry:
+ %cmp3.not = icmp eq i32 %N, 0
+ br i1 %cmp3.not, label %for.cond.cleanup, label %for.body
+
+for.cond.cleanup:
+ ret void
+
+for.body:
+ %i.04 = phi i32 [ %inc, %for.body ], [ 0, %entry ]
+ %rem = urem i32 %i.04, %rem_amt
+ tail call void @use.i32(i32 %rem)
+ %inc = add nuw i32 %i.04, 1
+ %exitcond.not = icmp eq i32 %inc, %N
+ br i1 %exitcond.not, label %for.cond.cleanup, label %for.body
+}
+
+define void @simple_urem_to_sel_nested2(i32 %N, i32 %rem_amt) nounwind {
+; CHECK-LABEL: simple_urem_to_sel_nested2:
+; CHECK: # %bb.0: # %entry
+; CHECK-NEXT: testl %edi, %edi
+; CHECK-NEXT: je .LBB1_8
+; CHECK-NEXT: # %bb.1: # %for.body.preheader
+; CHECK-NEXT: pushq %rbp
+; CHECK-NEXT: pushq %r15
+; CHECK-NEXT: pushq %r14
+; CHECK-NEXT: pushq %r12
+; CHECK-NEXT: pushq %rbx
+; CHECK-NEXT: movl %esi, %ebx
+; CHECK-NEXT: movl %edi, %ebp
+; CHECK-NEXT: xorl %r15d, %r15d
+; CHECK-NEXT: xorl %r14d, %r14d
+; CHECK-NEXT: xorl %r12d, %r12d
+; CHECK-NEXT: jmp .LBB1_2
+; CHECK-NEXT: .p2align 4, 0x90
+; CHECK-NEXT: .LBB1_5: # %for.body1
+; CHECK-NEXT: # in Loop: Header=BB1_2 Depth=1
+; CHECK-NEXT: movl %r14d, %edi
+; CHECK-NEXT: callq use.i32 at PLT
+; CHECK-NEXT: .LBB1_6: # %for.body.tail
+; CHECK-NEXT: # in Loop: Header=BB1_2 Depth=1
+; CHECK-NEXT: incl %r14d
+; CHECK-NEXT: cmpl %ebx, %r14d
+; CHECK-NEXT: cmovel %r15d, %r14d
+; CHECK-NEXT: incl %r12d
+; CHECK-NEXT: cmpl %r12d, %ebp
+; CHECK-NEXT: je .LBB1_7
+; CHECK-NEXT: .LBB1_2: # %for.body
+; CHECK-NEXT: # =>This Inner Loop Header: Depth=1
+; CHECK-NEXT: callq get.i1 at PLT
+; CHECK-NEXT: testb $1, %al
+; CHECK-NEXT: je .LBB1_6
+; CHECK-NEXT: # %bb.3: # %for.body0
+; CHECK-NEXT: # in Loop: Header=BB1_2 Depth=1
+; CHECK-NEXT: callq get.i1 at PLT
+; CHECK-NEXT: testb $1, %al
+; CHECK-NEXT: jne .LBB1_5
+; CHECK-NEXT: # %bb.4: # %for.body2
+; CHECK-NEXT: # in Loop: Header=BB1_2 Depth=1
+; CHECK-NEXT: callq get.i1 at PLT
+; CHECK-NEXT: testb $1, %al
+; CHECK-NEXT: jne .LBB1_5
+; CHECK-NEXT: jmp .LBB1_6
+; CHECK-NEXT: .LBB1_7:
+; CHECK-NEXT: popq %rbx
+; CHECK-NEXT: popq %r12
+; CHECK-NEXT: popq %r14
+; CHECK-NEXT: popq %r15
+; CHECK-NEXT: popq %rbp
+; CHECK-NEXT: .LBB1_8: # %for.cond.cleanup
+; CHECK-NEXT: retq
+entry:
+ %cmp3.not = icmp eq i32 %N, 0
+ br i1 %cmp3.not, label %for.cond.cleanup, label %for.body
+
+for.cond.cleanup:
+ ret void
+
+for.body:
+ %i.04 = phi i32 [ %inc, %for.body.tail ], [ 0, %entry ]
+ %cond0 = call i1 @get.i1()
+ br i1 %cond0, label %for.body0, label %for.body.tail
+for.body0:
+ %cond1 = call i1 @get.i1()
+ br i1 %cond1, label %for.body1, label %for.body2
+for.body2:
+ %cond2 = call i1 @get.i1()
+ br i1 %cond2, label %for.body1, label %for.body.tail
+for.body1:
+ %rem = urem i32 %i.04, %rem_amt
+ tail call void @use.i32(i32 %rem)
+ br label %for.body.tail
+for.body.tail:
+ %inc = add nuw i32 %i.04, 1
+ %exitcond.not = icmp eq i32 %inc, %N
+ br i1 %exitcond.not, label %for.cond.cleanup, label %for.body
+}
+
+define void @simple_urem_fail_bad_incr3(i32 %N, i32 %rem_amt) nounwind {
+; CHECK-LABEL: simple_urem_fail_bad_incr3:
+; CHECK: # %bb.0: # %entry
+; CHECK-NEXT: testl %edi, %edi
+; CHECK-NEXT: je .LBB2_9
+; CHECK-NEXT: # %bb.1:
+; CHECK-NEXT: pushq %rbp
+; CHECK-NEXT: pushq %r14
+; CHECK-NEXT: pushq %rbx
+; CHECK-NEXT: movl %esi, %ebx
+; CHECK-NEXT: jmp .LBB2_2
+; CHECK-NEXT: .p2align 4, 0x90
+; CHECK-NEXT: .LBB2_6: # %for.body1
+; CHECK-NEXT: # in Loop: Header=BB2_2 Depth=1
+; CHECK-NEXT: movl %ebp, %eax
+; CHECK-NEXT: xorl %edx, %edx
+; CHECK-NEXT: divl %ebx
+; CHECK-NEXT: movl %edx, %edi
+; CHECK-NEXT: callq use.i32 at PLT
+; CHECK-NEXT: .LBB2_7: # %for.body.tail
+; CHECK-NEXT: # in Loop: Header=BB2_2 Depth=1
+; CHECK-NEXT: callq get.i1 at PLT
+; CHECK-NEXT: testb $1, %al
+; CHECK-NEXT: jne .LBB2_8
+; CHECK-NEXT: .LBB2_2: # %for.body
+; CHECK-NEXT: # =>This Inner Loop Header: Depth=1
+; CHECK-NEXT: callq get.i1 at PLT
+; CHECK-NEXT: testb $1, %al
+; CHECK-NEXT: je .LBB2_5
+; CHECK-NEXT: # %bb.3: # %for.body0
+; CHECK-NEXT: # in Loop: Header=BB2_2 Depth=1
+; CHECK-NEXT: callq get.i1 at PLT
+; CHECK-NEXT: movl %eax, %r14d
+; CHECK-NEXT: callq get.i32 at PLT
+; CHECK-NEXT: testb $1, %r14b
+; CHECK-NEXT: je .LBB2_7
+; CHECK-NEXT: # %bb.4: # in Loop: Header=BB2_2 Depth=1
+; CHECK-NEXT: movl %eax, %ebp
+; CHECK-NEXT: incl %ebp
+; CHECK-NEXT: jmp .LBB2_6
+; CHECK-NEXT: .p2align 4, 0x90
+; CHECK-NEXT: .LBB2_5: # %for.body2
+; CHECK-NEXT: # in Loop: Header=BB2_2 Depth=1
+; CHECK-NEXT: xorl %ebp, %ebp
+; CHECK-NEXT: callq get.i1 at PLT
+; CHECK-NEXT: testb $1, %al
+; CHECK-NEXT: jne .LBB2_6
+; CHECK-NEXT: jmp .LBB2_7
+; CHECK-NEXT: .LBB2_8:
+; CHECK-NEXT: popq %rbx
+; CHECK-NEXT: popq %r14
+; CHECK-NEXT: popq %rbp
+; CHECK-NEXT: .LBB2_9: # %for.cond.cleanup
+; CHECK-NEXT: retq
+entry:
+ %cmp3.not = icmp eq i32 %N, 0
+ br i1 %cmp3.not, label %for.cond.cleanup, label %for.body
+
+for.cond.cleanup:
+ ret void
+
+for.body:
+ %cond0 = call i1 @get.i1()
+ br i1 %cond0, label %for.body0, label %for.body2
+for.body0:
+ %cond1 = call i1 @get.i1()
+ %val = call i32 @get.i32()
+ %inc = add nuw i32 %val, 1
+ br i1 %cond1, label %for.body1, label %for.body.tail
+for.body2:
+ %cond2 = call i1 @get.i1()
+ br i1 %cond2, label %for.body1, label %for.body.tail
+for.body1:
+ %i.04 = phi i32 [ %inc, %for.body0], [ 0, %for.body2 ]
+ %rem = urem i32 %i.04, %rem_amt
+ tail call void @use.i32(i32 %rem)
+ br label %for.body.tail
+for.body.tail:
+ %exitcond.not = call i1 @get.i1()
+ br i1 %exitcond.not, label %for.cond.cleanup, label %for.body
+}
+
+define void @simple_urem_to_sel_vec(<2 x i64> %rem_amt) nounwind {
+; CHECK-LABEL: simple_urem_to_sel_vec:
+; CHECK: # %bb.0: # %entry
+; CHECK-NEXT: subq $56, %rsp
+; CHECK-NEXT: movdqa %xmm0, {{[-0-9]+}}(%r{{[sb]}}p) # 16-byte Spill
+; CHECK-NEXT: pxor %xmm1, %xmm1
+; CHECK-NEXT: pxor %xmm0, %xmm0
+; CHECK-NEXT: movdqa %xmm0, {{[-0-9]+}}(%r{{[sb]}}p) # 16-byte Spill
+; CHECK-NEXT: .p2align 4, 0x90
+; CHECK-NEXT: .LBB3_1: # %for.body
+; CHECK-NEXT: # =>This Inner Loop Header: Depth=1
+; CHECK-NEXT: movdqa %xmm1, (%rsp) # 16-byte Spill
+; CHECK-NEXT: movdqa %xmm1, %xmm0
+; CHECK-NEXT: callq use.2xi64 at PLT
+; CHECK-NEXT: pcmpeqd %xmm1, %xmm1
+; CHECK-NEXT: movdqa (%rsp), %xmm2 # 16-byte Reload
+; CHECK-NEXT: psubq %xmm1, %xmm2
+; CHECK-NEXT: movdqa %xmm2, %xmm0
+; CHECK-NEXT: movdqa %xmm2, %xmm3
+; CHECK-NEXT: pcmpeqd {{[-0-9]+}}(%r{{[sb]}}p), %xmm0 # 16-byte Folded Reload
+; CHECK-NEXT: pshufd {{.*#+}} xmm2 = xmm0[1,0,3,2]
+; CHECK-NEXT: pand %xmm0, %xmm2
+; CHECK-NEXT: pandn %xmm3, %xmm2
+; CHECK-NEXT: movdqa %xmm2, (%rsp) # 16-byte Spill
+; CHECK-NEXT: movdqa {{[-0-9]+}}(%r{{[sb]}}p), %xmm0 # 16-byte Reload
+; CHECK-NEXT: psubq %xmm1, %xmm0
+; CHECK-NEXT: movdqa %xmm0, {{[-0-9]+}}(%r{{[sb]}}p) # 16-byte Spill
+; CHECK-NEXT: callq get.i1 at PLT
+; CHECK-NEXT: testb $1, %al
+; CHECK-NEXT: movdqa (%rsp), %xmm1 # 16-byte Reload
+; CHECK-NEXT: je .LBB3_1
+; CHECK-NEXT: # %bb.2: # %for.cond.cleanup
+; CHECK-NEXT: addq $56, %rsp
+; CHECK-NEXT: retq
+entry:
+ br label %for.body
+
+for.cond.cleanup:
+ ret void
+
+for.body:
+ %i.04 = phi <2 x i64> [ %inc, %for.body ], [ zeroinitializer, %entry ]
+ %rem = urem <2 x i64> %i.04, %rem_amt
+ tail call void @use.2xi64(<2 x i64> %rem)
+ %inc = add nuw <2 x i64> %i.04, <i64 1, i64 1>
+ %exitcond.not = call i1 @get.i1()
+ br i1 %exitcond.not, label %for.cond.cleanup, label %for.body
+}
+
+define void @simple_urem_fail_bad_incr(i32 %N, i32 %rem_amt) nounwind {
+; CHECK-LABEL: simple_urem_fail_bad_incr:
+; CHECK: # %bb.0: # %entry
+; CHECK-NEXT: testl %edi, %edi
+; CHECK-NEXT: je .LBB4_6
+; CHECK-NEXT: # %bb.1: # %for.body.preheader
+; CHECK-NEXT: pushq %rbp
+; CHECK-NEXT: pushq %r14
+; CHECK-NEXT: pushq %rbx
+; CHECK-NEXT: movl %esi, %ebx
+; CHECK-NEXT: movl %edi, %ebp
+; CHECK-NEXT: xorl %r14d, %r14d
+; CHECK-NEXT: jmp .LBB4_2
+; CHECK-NEXT: .p2align 4, 0x90
+; CHECK-NEXT: .LBB4_4: # %for.body.tail
+; CHECK-NEXT: # in Loop: Header=BB4_2 Depth=1
+; CHECK-NEXT: movl %r14d, %eax
+; CHECK-NEXT: xorl %edx, %edx
+; CHECK-NEXT: divl %ebx
+; CHECK-NEXT: movl %edx, %edi
+; CHECK-NEXT: callq use.i32 at PLT
+; CHECK-NEXT: incl %r14d
+; CHECK-NEXT: cmpl %ebp, %r14d
+; CHECK-NEXT: je .LBB4_5
+; CHECK-NEXT: .LBB4_2: # %for.body
+; CHECK-NEXT: # =>This Inner Loop Header: Depth=1
+; CHECK-NEXT: callq get.i1 at PLT
+; CHECK-NEXT: testb $1, %al
+; CHECK-NEXT: je .LBB4_4
+; CHECK-NEXT: # %bb.3: # %for.body0
+; CHECK-NEXT: # in Loop: Header=BB4_2 Depth=1
+; CHECK-NEXT: callq get.i32 at PLT
+; CHECK-NEXT: movl %eax, %r14d
+; CHECK-NEXT: jmp .LBB4_4
+; CHECK-NEXT: .LBB4_5:
+; CHECK-NEXT: popq %rbx
+; CHECK-NEXT: popq %r14
+; CHECK-NEXT: popq %rbp
+; CHECK-NEXT: .LBB4_6: # %for.cond.cleanup
+; CHECK-NEXT: retq
+entry:
+ %cmp3.not = icmp eq i32 %N, 0
+ br i1 %cmp3.not, label %for.cond.cleanup, label %for.body
+
+for.cond.cleanup:
+ ret void
+
+for.body:
+ %i.03 = phi i32 [ %inc, %for.body.tail ], [ 0, %entry ]
+ %cond0 = call i1 @get.i1()
+ br i1 %cond0, label %for.body0, label %for.body.tail
+for.body0:
+ %some_val = call i32 @get.i32()
+ br label %for.body.tail
+
+for.body.tail:
+ %i.04 = phi i32 [ %i.03, %for.body ], [ %some_val, %for.body0 ]
+ %rem = urem i32 %i.04, %rem_amt
+ tail call void @use.i32(i32 %rem)
+ %inc = add nuw i32 %i.04, 1
+ %exitcond.not = icmp eq i32 %inc, %N
+ br i1 %exitcond.not, label %for.cond.cleanup, label %for.body
+}
+
+define void @simple_urem_to_sel_second_acc(i32 %N, i32 %rem_amt) nounwind {
+; CHECK-LABEL: simple_urem_to_sel_second_acc:
+; CHECK: # %bb.0: # %entry
+; CHECK-NEXT: cmpl $2, %edi
+; CHECK-NEXT: jb .LBB5_4
+; CHECK-NEXT: # %bb.1: # %for.body.preheader
+; CHECK-NEXT: pushq %rbp
+; CHECK-NEXT: pushq %r15
+; CHECK-NEXT: pushq %r14
+; CHECK-NEXT: pushq %r13
+; CHECK-NEXT: pushq %r12
+; CHECK-NEXT: pushq %rbx
+; CHECK-NEXT: pushq %rax
+; CHECK-NEXT: movl %esi, %ebx
+; CHECK-NEXT: movl %edi, %ebp
+; CHECK-NEXT: movl $1, %r15d
+; CHECK-NEXT: xorl %r12d, %r12d
+; CHECK-NEXT: xorl %r14d, %r14d
+; CHECK-NEXT: xorl %r13d, %r13d
+; CHECK-NEXT: .p2align 4, 0x90
+; CHECK-NEXT: .LBB5_2: # %for.body
+; CHECK-NEXT: # =>This Inner Loop Header: Depth=1
+; CHECK-NEXT: movl %r14d, %edi
+; CHECK-NEXT: callq use.i32 at PLT
+; CHECK-NEXT: incl %r14d
+; CHECK-NEXT: cmpl %ebx, %r14d
+; CHECK-NEXT: cmovel %r12d, %r14d
+; CHECK-NEXT: incl %r13d
+; CHECK-NEXT: addl $2, %r15d
+; CHECK-NEXT: cmpl %ebp, %r15d
+; CHECK-NEXT: jbe .LBB5_2
+; CHECK-NEXT: # %bb.3:
+; CHECK-NEXT: addq $8, %rsp
+; CHECK-NEXT: popq %rbx
+; CHECK-NEXT: popq %r12
+; CHECK-NEXT: popq %r13
+; CHECK-NEXT: popq %r14
+; CHECK-NEXT: popq %r15
+; CHECK-NEXT: popq %rbp
+; CHECK-NEXT: .LBB5_4: # %for.cond.cleanup
+; CHECK-NEXT: retq
+entry:
+ %cmp3.not = icmp ult i32 %N, 2
+ br i1 %cmp3.not, label %for.cond.cleanup, label %for.body
+
+for.cond.cleanup:
+ ret void
+
+for.body:
+ %i.04 = phi i32 [ %inc, %for.body ], [ 0, %entry ]
+ %i.05 = phi i32 [ %inc2, %for.body ], [ 1, %entry ]
+ %rem = urem i32 %i.04, %rem_amt
+ tail call void @use.i32(i32 %rem)
+ %inc = add nuw i32 %i.04, 1
+ %inc2 = add nuw i32 %i.05, 2
+ %exitcond.not = icmp ugt i32 %inc2, %N
+ br i1 %exitcond.not, label %for.cond.cleanup, label %for.body
+}
+
+define void @simple_urem_fail_srem(i32 %N, i32 %rem_amt) nounwind {
+; CHECK-LABEL: simple_urem_fail_srem:
+; CHECK: # %bb.0: # %entry
+; CHECK-NEXT: testl %edi, %edi
+; CHECK-NEXT: je .LBB6_4
+; CHECK-NEXT: # %bb.1: # %for.body.preheader
+; CHECK-NEXT: pushq %rbp
+; CHECK-NEXT: pushq %r14
+; CHECK-NEXT: pushq %rbx
+; CHECK-NEXT...
[truncated]
``````````
</details>
https://github.com/llvm/llvm-project/pull/96625
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