[llvm] Reapply "[InstCombine] Merge consecutive assumes", round 3 (PR #225380)
Nikolas Klauser via llvm-commits
llvm-commits at lists.llvm.org
Tue Sep 22 05:08:39 PDT 2026
https://github.com/philnik777 created https://github.com/llvm/llvm-project/pull/225380
This patch was reverted due to triggering another bug. That bug should
be fixed now, so this should be ready to land again.
Original commit message:
This should make assumes a bit more efficient, since it removes a few
instructions. This should also help with optimizations that are limited
in how many instructions they step through.
This reverts commit 630125ac5be7dab26fcfba8918ee091588616f21.
>From dc131aa6c533fb38feb831c66eff19d91aa6bb27 Mon Sep 17 00:00:00 2001
From: Nikolas Klauser <nikolasklauser at berlin.de>
Date: Tue, 22 Sep 2026 14:05:40 +0200
Subject: [PATCH] Reapply "[InstCombine] Merge consecutive assumes", round 3
This patch was reverted due to triggering another bug. That bug should
be fixed now, so this should be ready to land again.
Original commit message:
This should make assumes a bit more efficient, since it removes a few
instructions. This should also help with optimizations that are limited
in how many instructions they step through.
This reverts commit 630125ac5be7dab26fcfba8918ee091588616f21.
---
llvm/include/llvm/IR/InstrTypes.h | 6 ++++
.../InstCombine/InstCombineCalls.cpp | 22 ++++++++++--
.../InstCombine/InstructionCombining.cpp | 2 +-
.../InstCombine/assume-loop-align.ll | 3 +-
llvm/test/Transforms/InstCombine/assume.ll | 36 +++++++++++--------
.../PhaseOrdering/AArch64/std-find.ll | 3 +-
6 files changed, 50 insertions(+), 22 deletions(-)
diff --git a/llvm/include/llvm/IR/InstrTypes.h b/llvm/include/llvm/IR/InstrTypes.h
index 5f7df6a4eb6f8..681c4b18375f4 100644
--- a/llvm/include/llvm/IR/InstrTypes.h
+++ b/llvm/include/llvm/IR/InstrTypes.h
@@ -2359,6 +2359,12 @@ class CallBase : public Instruction {
});
}
+ /// Return whether there exists an operand bundle of type ID
+ bool hasOperandBundle(uint32_t ID) const {
+ return any_of(operand_bundles(),
+ [&](OperandBundleUse OBU) { return OBU.getTagID() == ID; });
+ }
+
/// Populate the BundleOpInfo instances and the Use& vector from \p
/// Bundles. Return the op_iterator pointing to the Use& one past the last
/// last bundle operand use.
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 86dd4397f22c9..83af96edfb26e 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -4003,10 +4003,26 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {
}
}
- // If the assume has operand bundles, the folds below will never work, so
- // don't bother trying.
- if (II->hasOperandBundles())
+ if (II->hasOperandBundles()) {
+ // Merge consecutive assumes to save some resources
+ if (auto *PrevAI = dyn_cast_or_null<AssumeInst>(II->getPrevNode());
+ PrevAI && PrevAI->hasOperandBundles()) {
+ SmallVector<OperandBundleDef, 4> Bundles;
+ Bundles.reserve(II->getNumOperandBundles() +
+ PrevAI->getNumOperandBundles());
+ for (auto Bundle : PrevAI->operand_bundles())
+ Bundles.emplace_back(Bundle);
+ for (auto Bundle : II->operand_bundles())
+ Bundles.emplace_back(Bundle);
+ Builder.CreateAssumption(Bundles);
+ eraseInstFromFunction(*PrevAI);
+ return eraseInstFromFunction(*II);
+ }
+
+ // If the assume has operand bundles, the folds below will never work, so
+ // don't bother trying.
break;
+ }
Value *IIOperand = II->getArgOperand(0);
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 4b09510933d0c..59a0a3ad96c65 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -5810,7 +5810,7 @@ bool InstCombinerImpl::run() {
// removed.
auto II = dyn_cast<IntrinsicInst>(User);
if (II->getIntrinsicID() != Intrinsic::assume ||
- !II->getOperandBundle("dereferenceable"))
+ !II->hasOperandBundle(LLVMContext::OB_Dereferenceable))
continue;
}
diff --git a/llvm/test/Transforms/InstCombine/assume-loop-align.ll b/llvm/test/Transforms/InstCombine/assume-loop-align.ll
index 0c5e403ca54a9..2701775f011e8 100644
--- a/llvm/test/Transforms/InstCombine/assume-loop-align.ll
+++ b/llvm/test/Transforms/InstCombine/assume-loop-align.ll
@@ -10,8 +10,7 @@ target triple = "x86_64-unknown-linux-gnu"
define void @foo(ptr %a, ptr %b) #0 {
; CHECK-LABEL: @foo(
; CHECK-NEXT: entry:
-; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[A:%.*]], i64 64) ]
-; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[B:%.*]], i64 64) ]
+; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[A:%.*]], i64 64), "align"(ptr [[B:%.*]], i64 64) ]
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[INDVARS_IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INDVARS_IV_NEXT:%.*]], [[FOR_BODY]] ]
diff --git a/llvm/test/Transforms/InstCombine/assume.ll b/llvm/test/Transforms/InstCombine/assume.ll
index ff59947939a60..dc43933ba68e1 100644
--- a/llvm/test/Transforms/InstCombine/assume.ll
+++ b/llvm/test/Transforms/InstCombine/assume.ll
@@ -138,8 +138,7 @@ define i1 @align_with_offset_on_gep(ptr %base) {
define void @align_with_constant_offset_0(ptr %ptr) {
; CHECK-LABEL: @align_with_constant_offset_0(
-; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[PTR:%.*]], i64 16) ]
-; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[PTR]], i64 8, i64 0) ]
+; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[PTR:%.*]], i64 16), "align"(ptr [[PTR]], i64 8, i64 0) ]
; CHECK-NEXT: ret void
;
call void @llvm.assume(i1 true) [ "align"(ptr %ptr, i64 16) ]
@@ -149,8 +148,7 @@ define void @align_with_constant_offset_0(ptr %ptr) {
define void @align_with_constant_offset_1(ptr %ptr) {
; CHECK-LABEL: @align_with_constant_offset_1(
-; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[PTR:%.*]], i64 16) ]
-; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[PTR]], i64 8, i64 -8) ]
+; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[PTR:%.*]], i64 16), "align"(ptr [[PTR]], i64 8, i64 -8) ]
; CHECK-NEXT: ret void
;
call void @llvm.assume(i1 true) [ "align"(ptr %ptr, i64 16) ]
@@ -161,8 +159,7 @@ define void @align_with_constant_offset_1(ptr %ptr) {
define void @align_with_constant_offset_4(ptr %ptr) {
; CHECK-LABEL: @align_with_constant_offset_4(
-; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[PTR:%.*]], i64 16) ]
-; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[PTR]], i64 8, i64 0) ]
+; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[PTR:%.*]], i64 16), "align"(ptr [[PTR]], i64 8, i64 0) ]
; CHECK-NEXT: ret void
;
call void @llvm.assume(i1 true) [ "align"(ptr %ptr, i64 16) ]
@@ -173,8 +170,7 @@ define void @align_with_constant_offset_4(ptr %ptr) {
define void @align_with_constant_offset_8(ptr %ptr) {
; CHECK-LABEL: @align_with_constant_offset_8(
-; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[PTR:%.*]], i64 16) ]
-; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[PTR]], i64 8, i64 8) ]
+; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[PTR:%.*]], i64 16), "align"(ptr [[PTR]], i64 8, i64 8) ]
; CHECK-NEXT: ret void
;
call void @llvm.assume(i1 true) [ "align"(ptr %ptr, i64 16) ]
@@ -184,8 +180,7 @@ define void @align_with_constant_offset_8(ptr %ptr) {
define void @align_with_variable_offset(ptr %ptr, i64 %offset) {
; CHECK-LABEL: @align_with_variable_offset(
-; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[PTR:%.*]], i64 16) ]
-; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[PTR]], i64 8, i64 [[OFFSET:%.*]]) ]
+; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[PTR:%.*]], i64 16), "align"(ptr [[PTR]], i64 8, i64 [[OFFSET:%.*]]) ]
; CHECK-NEXT: ret void
;
call void @llvm.assume(i1 true) [ "align"(ptr %ptr, i64 16) ]
@@ -650,10 +645,7 @@ define void @redundant_nonnull3(ptr %ptr) {
define void @partially_redundant(ptr %ptr, ptr %ptr2, ptr %ptr3, ptr %ptr4, ptr %ptr5) {
; CHECK-LABEL: @partially_redundant(
-; CHECK-NEXT: call void @llvm.assume(i1 true) [ "nonnull"(ptr [[PTR2:%.*]]) ]
-; CHECK-NEXT: call void @llvm.assume(i1 true) [ "nonnull"(ptr [[PTR:%.*]]) ]
-; CHECK-NEXT: call void @llvm.assume(i1 true) [ "nonnull"(ptr [[PTR4:%.*]]), "nonnull"(ptr [[PTR3:%.*]]) ]
-; CHECK-NEXT: call void @llvm.assume(i1 true) [ "nonnull"(ptr [[PTR5:%.*]]) ]
+; CHECK-NEXT: call void @llvm.assume(i1 true) [ "nonnull"(ptr [[PTR5:%.*]]), "nonnull"(ptr [[PTR4:%.*]]), "nonnull"(ptr [[PTR3:%.*]]), "nonnull"(ptr [[PTR:%.*]]), "nonnull"(ptr [[PTR2:%.*]]) ]
; CHECK-NEXT: ret void
;
call void @llvm.assume(i1 true) [ "nonnull"(ptr %ptr), "nonnull"(ptr %ptr2) ]
@@ -1433,6 +1425,22 @@ define i32 @assume_noundef_on_load_after_call(ptr %ptr) {
ret i32 %val
}
+define ptr @avoid_get_operand_bundle() {
+; CHECK-LABEL: @avoid_get_operand_bundle(
+; CHECK-NEXT: bb:
+; CHECK-NEXT: [[LOAD:%.*]] = load volatile ptr, ptr null, align 8
+; CHECK-NEXT: [[PTRTOINT_I:%.*]] = ptrtoint ptr [[LOAD]] to i64
+; CHECK-NEXT: call void @llvm.assume(i1 true) [ "dereferenceable"(ptr null, i64 [[PTRTOINT_I]]), "dereferenceable"(ptr null, i64 [[PTRTOINT_I]]) ]
+; CHECK-NEXT: ret ptr null
+;
+bb:
+ %load = load volatile ptr, ptr null, align 8
+ %ptrtoint.i = ptrtoint ptr %load to i64
+ call void @llvm.assume(i1 true) [ "dereferenceable"(ptr null, i64 %ptrtoint.i) ]
+ call void @llvm.assume(i1 true) [ "dereferenceable"(ptr null, i64 %ptrtoint.i) ]
+ ret ptr null
+}
+
declare void @use(i1)
declare void @block()
declare void @llvm.dbg.value(metadata, metadata, metadata)
diff --git a/llvm/test/Transforms/PhaseOrdering/AArch64/std-find.ll b/llvm/test/Transforms/PhaseOrdering/AArch64/std-find.ll
index 5941eb6fa8046..9c180ed1a25fc 100644
--- a/llvm/test/Transforms/PhaseOrdering/AArch64/std-find.ll
+++ b/llvm/test/Transforms/PhaseOrdering/AArch64/std-find.ll
@@ -244,8 +244,7 @@ define ptr @std_find_caller(ptr noundef %first, ptr noundef %last) {
; CHECK-LABEL: define noundef ptr @std_find_caller(
; CHECK-SAME: ptr noundef [[FIRST:%.*]], ptr noundef [[LAST:%.*]]) local_unnamed_addr #[[ATTR0]] {
; CHECK-NEXT: [[ENTRY:.*]]:
-; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[FIRST]], i64 2) ]
-; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[LAST]], i64 2) ]
+; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[FIRST]], i64 2), "align"(ptr [[LAST]], i64 2) ]
; CHECK-NEXT: [[PRE_I:%.*]] = icmp eq ptr [[FIRST]], [[LAST]]
; CHECK-NEXT: br i1 [[PRE_I]], label %[[STD_FIND_GENERIC_IMPL_EXIT:.*]], label %[[LOOP_HEADER_I_PREHEADER:.*]]
; CHECK: [[LOOP_HEADER_I_PREHEADER]]:
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