Teach X86FastISel to fold constant offsets and scaled indices in

the same address.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107373 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/X86FastISel.cpp b/lib/Target/X86/X86FastISel.cpp
index 0338203d35d9e420868f584117c988b1e836fd6c..f371796141d51a7016853eee9c72e86376e4a318 100644 (file)
--- a/lib/Target/X86/X86FastISel.cpp
+++ b/lib/Target/X86/X86FastISel.cpp
@@ -423,20 +423,29 @@ bool X86FastISel::X86SelectAddress(const Value *V, X86AddressMode &AM) {
         Disp += SL->getElementOffset(Idx);
       } else {
         uint64_t S = TD.getTypeAllocSize(GTI.getIndexedType());
-        if (const ConstantInt *CI = dyn_cast<ConstantInt>(Op)) {
-          // Constant-offset addressing.
-          Disp += CI->getSExtValue() * S;
-        } else if (IndexReg == 0 &&
-                   (!AM.GV || !Subtarget->isPICStyleRIPRel()) &&
-                   (S == 1 || S == 2 || S == 4 || S == 8)) {
-          // Scaled-index addressing.
-          Scale = S;
-          IndexReg = getRegForGEPIndex(Op).first;
-          if (IndexReg == 0)
-            return false;
-        } else
-          // Unsupported.
-          goto unsupported_gep;
+        SmallVector<const Value *, 4> Worklist;
+        Worklist.push_back(Op);
+        do {
+          Op = Worklist.pop_back_val();
+          if (const ConstantInt *CI = dyn_cast<ConstantInt>(Op)) {
+            // Constant-offset addressing.
+            Disp += CI->getSExtValue() * S;
+          } else if (IndexReg == 0 &&
+                     (!AM.GV || !Subtarget->isPICStyleRIPRel()) &&
+                     (S == 1 || S == 2 || S == 4 || S == 8)) {
+            // Scaled-index addressing.
+            Scale = S;
+            IndexReg = getRegForGEPIndex(Op).first;
+            if (IndexReg == 0)
+              return false;
+          } else if (const AddOperator *Add = dyn_cast<AddOperator>(Op)) {
+            // An add. Try to fold both operands.
+            Worklist.push_back(Add->getOperand(0));
+            Worklist.push_back(Add->getOperand(1));
+          } else
+            // Unsupported.
+            goto unsupported_gep;
+        } while (!Worklist.empty());
       }
     }
     // Check for displacement overflow.

diff --git a/test/CodeGen/X86/fast-isel-gep.ll b/test/CodeGen/X86/fast-isel-gep.ll
index 5b8acecc3c18c8b8aae4a9177650d62a83e9c177..1270ab78ab5f748b2456eb7bf023cf884b991658 100644 (file)
--- a/test/CodeGen/X86/fast-isel-gep.ll
+++ b/test/CodeGen/X86/fast-isel-gep.ll
@@ -51,3 +51,22 @@ entry:
 ; X64:         ret
 
 }
+
+define double @test4(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]
+  %add = add nsw i64 %tmp, 16                     ; <i64> [#uses=1]
+  %tmp1 = load double** %p.addr                   ; <double*> [#uses=1]
+  %arrayidx = getelementptr inbounds double* %tmp1, i64 %add ; <double*> [#uses=1]
+  %tmp2 = load double* %arrayidx                  ; <double> [#uses=1]
+  ret double %tmp2
+
+; X32: test4:
+; X32: 128(%e{{.*}},%e{{.*}},8)
+; X64: test4:
+; X64: 128(%r{{.*}},%r{{.*}},8)
+}