#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/PatternMatch.h"
#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/RecyclingAllocator.h"
#include "llvm/Transforms/Utils/Local.h"
#include <deque>
using namespace llvm;
+using namespace llvm::PatternMatch;
#define DEBUG_TYPE "early-cse"
continue;
}
+ // Skip assume intrinsics, they don't really have side effects (although
+ // they're marked as such to ensure preservation of control dependencies),
+ // and this pass will not disturb any of the assumption's control
+ // dependencies.
+ if (match(Inst, m_Intrinsic<Intrinsic::assume>())) {
+ DEBUG(dbgs() << "EarlyCSE skipping assumption: " << *Inst << '\n');
+ continue;
+ }
+
// If the instruction can be simplified (e.g. X+0 = X) then replace it with
// its simpler value.
if (Value *V = SimplifyInstruction(Inst, DL, TLI, DT, AT)) {
; RUN: opt < %s -S -early-cse | FileCheck %s
+declare void @llvm.assume(i1) nounwind
; CHECK-LABEL: @test1(
define void @test1(i8 %V, i32 *%P) {
; CHECK: ret i32 0
}
+; CHECK-LABEL: @test2a(
+define i32 @test2a(i32 *%P, i1 %b) {
+ %V1 = load i32* %P
+ tail call void @llvm.assume(i1 %b)
+ %V2 = load i32* %P
+ %Diff = sub i32 %V1, %V2
+ ret i32 %Diff
+ ; CHECK: ret i32 0
+}
+
;; Cross block load value numbering.
; CHECK-LABEL: @test3(
define i32 @test3(i32 *%P, i1 %Cond) {
; CHECK: ret i32 0
}
+; CHECK-LABEL: @test3a(
+define i32 @test3a(i32 *%P, i1 %Cond, i1 %b) {
+ %V1 = load i32* %P
+ br i1 %Cond, label %T, label %F
+T:
+ store i32 4, i32* %P
+ ret i32 42
+F:
+ tail call void @llvm.assume(i1 %b)
+ %V2 = load i32* %P
+ %Diff = sub i32 %V1, %V2
+ ret i32 %Diff
+ ; CHECK: F:
+ ; CHECK: ret i32 0
+}
+
;; Cross block load value numbering stops when stores happen.
; CHECK-LABEL: @test4(
define i32 @test4(i32 *%P, i1 %Cond) {
; CHECK: ret i32 42
}
+; CHECK-LABEL: @test6a(
+define i32 @test6a(i32 *%P, i1 %b) {
+ store i32 42, i32* %P
+ tail call void @llvm.assume(i1 %b)
+ %V1 = load i32* %P
+ ret i32 %V1
+ ; CHECK: ret i32 42
+}
+
;; Trivial dead store elimination.
; CHECK-LABEL: @test7(
define void @test7(i32 *%P) {