[llvm] 2c1d884 - Reapply "[InstCombine] Merge consecutive assumes", round 2 (#205773)
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Thu Jun 25 04:56:14 PDT 2026
Author: Nikolas Klauser
Date: 2026-06-25T13:56:09+02:00
New Revision: 2c1d884c47b03e35283639f7122499ded8986b2b
URL: https://github.com/llvm/llvm-project/commit/2c1d884c47b03e35283639f7122499ded8986b2b
DIFF: https://github.com/llvm/llvm-project/commit/2c1d884c47b03e35283639f7122499ded8986b2b.diff
LOG: Reapply "[InstCombine] Merge consecutive assumes", round 2 (#205773)
This patch was reverted due to triggering another bug. That bug has been
fixed by https://github.com/llvm/llvm-project/pull/205275, so this
should be ready to land now.
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 053d75c1d580e0c394f4cfb0688bafd05c187b0f.
Added:
Modified:
llvm/include/llvm/IR/InstrTypes.h
llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
llvm/test/Transforms/InstCombine/assume-loop-align.ll
llvm/test/Transforms/InstCombine/assume.ll
llvm/test/Transforms/PhaseOrdering/AArch64/std-find.ll
Removed:
################################################################################
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 ce9e4b836a56e..880d896e12d6e 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -3844,10 +3844,26 @@ 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 1e24ff8d51057..ece0b36a15b72 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -5849,7 +5849,7 @@ 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 69220811ac206..8c819ad17a1f3 100644
--- a/llvm/test/Transforms/InstCombine/assume.ll
+++ b/llvm/test/Transforms/InstCombine/assume.ll
@@ -134,8 +134,7 @@ 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) ]
@@ -145,8 +144,7 @@ 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) ]
@@ -157,8 +155,7 @@ 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) ]
@@ -169,8 +166,7 @@ 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) ]
@@ -180,8 +176,7 @@ 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) ]
@@ -627,10 +622,7 @@ 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) ]
@@ -1392,6 +1384,22 @@ 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 69b23200b239b..4ca7f780cdc5e 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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