Delete fast-isel's trivial load optimization; it breaks debugging because

it can look past points where a debugger might modify user variables.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108336 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/CodeGen/FastISel.h b/include/llvm/CodeGen/FastISel.h
index 7c576483774507aab6c4b66c257cf7ac9e45a6e3..79b1554e22ac72a093042004588ffbf4c455104c 100644 (file)
--- a/include/llvm/CodeGen/FastISel.h
+++ b/include/llvm/CodeGen/FastISel.h
@@ -307,8 +307,6 @@ protected:
   }
 
 private:
-  bool SelectLoad(const User *I);
-
   bool SelectBinaryOp(const User *I, unsigned ISDOpcode);
 
   bool SelectFNeg(const User *I);

diff --git a/lib/CodeGen/SelectionDAG/FastISel.cpp b/lib/CodeGen/SelectionDAG/FastISel.cpp
index bd49c179804181babb11fbd145ec184d2629f4b4..6c13f27199e8f563e4c702c14d292034c3c4887d 100644 (file)
--- a/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -781,40 +781,9 @@ FastISel::SelectFNeg(const User *I) {
   return true;
 }
 
-bool
-FastISel::SelectLoad(const User *I) {
-  LoadInst *LI = const_cast<LoadInst *>(cast<LoadInst>(I));
-
-  // For a load from an alloca, make a limited effort to find the value
-  // already available in a register, avoiding redundant loads.
-  if (!LI->isVolatile() && isa<AllocaInst>(LI->getPointerOperand())) {
-    BasicBlock::iterator ScanFrom = LI;
-    if (const Value *V = FindAvailableLoadedValue(LI->getPointerOperand(),
-                                                  LI->getParent(), ScanFrom)) {
-      if (!V->use_empty() &&
-          (!isa<Instruction>(V) ||
-           cast<Instruction>(V)->getParent() == LI->getParent() ||
-           (isa<AllocaInst>(V) &&
-            FuncInfo.StaticAllocaMap.count(cast<AllocaInst>(V)))) &&
-          (!isa<Argument>(V) ||
-           LI->getParent() == &LI->getParent()->getParent()->getEntryBlock())) {
-      unsigned ResultReg = getRegForValue(V);
-      if (ResultReg != 0) {
-        UpdateValueMap(I, ResultReg);
-        return true;
-      }
-      }
-    }
-  }
-
-  return false;
-}
-
 bool
 FastISel::SelectOperator(const User *I, unsigned Opcode) {
   switch (Opcode) {
-  case Instruction::Load:
-    return SelectLoad(I);
   case Instruction::Add:
     return SelectBinaryOp(I, ISD::ADD);
   case Instruction::FAdd:

diff --git a/test/CodeGen/X86/fast-isel-loads.ll b/test/CodeGen/X86/fast-isel-loads.ll
deleted file mode 100644 (file)
index 2fbb46c..0000000
--- a/test/CodeGen/X86/fast-isel-loads.ll
+++ /dev/null
@@ -1,23 +0,0 @@
-; RUN: llc -march=x86-64 -O0 -asm-verbose=false < %s | FileCheck %s
-
-; Fast-isel shouldn't reload the argument values from the stack.
-
-; CHECK: foo:
-; CHECK-NEXT: movq  %rdi, -8(%rsp)
-; CHECK-NEXT: movq  %rsi, -16(%rsp)
-; CHECK-NEXT: movsd 128(%rsi,%rdi,8), %xmm0
-; CHECK-NEXT: ret
-
-define double @foo(i64 %x, double* %p) nounwind {
-entry:
-  %x.addr = alloca i64, align 8                   ; <i64*> [#uses=2]
-  %p.addr = alloca double*, align 8               ; <double**> [#uses=2]
-  store i64 %x, i64* %x.addr
-  store double* %p, double** %p.addr
-  %tmp = load i64* %x.addr                        ; <i64> [#uses=1]
-  %tmp1 = load double** %p.addr                   ; <double*> [#uses=1]
-  %add = add nsw i64 %tmp, 16                     ; <i64> [#uses=1]
-  %arrayidx = getelementptr inbounds double* %tmp1, i64 %add ; <double*> [#uses=1]
-  %tmp2 = load double* %arrayidx                  ; <double> [#uses=1]
-  ret double %tmp2
-}