[MSan] [MIPS64] Fix vararg helper for >1 fixed argument.

[• koriakin]

Summary

This fixes http://llvm.org/PR27646 on Mips64.

lib/Transforms/Instrumentation/MemorySanitizer.cpp

struct VarArgMIPS64Helper : public VarArgHelper {
   VarArgMIPS64Helper(Function &F, MemorySanitizer &MS,
                     MemorySanitizerVisitor &MSV)
     : F(F), MS(MS), MSV(MSV), VAArgTLSCopy(nullptr),
       VAArgSize(nullptr) {}
 
   void visitCallSite(CallSite &CS, IRBuilder<> &IRB) override {
     unsigned VAArgOffset = 0;
     const DataLayout &DL = F.getParent()->getDataLayout();
-    for (CallSite::arg_iterator ArgIt = CS.arg_begin() + 1, End = CS.arg_end();
+    for (CallSite::arg_iterator ArgIt = CS.arg_begin() +
+         CS.getFunctionType()->getNumParams(), End = CS.arg_end();
          ArgIt != End; ++ArgIt) {
       llvm::Triple TargetTriple(F.getParent()->getTargetTriple());
       Value *A = *ArgIt;
       Value *Base;
       uint64_t ArgSize = DL.getTypeAllocSize(A->getType());
       if (TargetTriple.getArch() == llvm::Triple::mips64) {
         // Adjusting the shadow for argument with size < 8 to match the placement
         // of bits in big endian system

test/Instrumentation/MemorySanitizer/Mips/vararg-mips64.ll

 ; Save the incoming shadow value from the arguments in the __msan_va_arg_tls
 ; array.  The first argument is stored at position 4, since it's right
 ; justified.
 ; CHECK-LABEL: @bar
 ; CHECK: store i32 0, i32* inttoptr (i64 add (i64 ptrtoint ([100 x i64]* @__msan_va_arg_tls to i64), i64 4) to i32*), align 8
 ; CHECK: store i64 0, i64* inttoptr (i64 add (i64 ptrtoint ([100 x i64]* @__msan_va_arg_tls to i64), i64 8) to i64*), align 8
 ; CHECK: store i64 0, i64* inttoptr (i64 add (i64 ptrtoint ([100 x i64]* @__msan_va_arg_tls to i64), i64 16) to i64*), align 8
 ; CHECK: store {{.*}} 24, {{.*}} @__msan_va_arg_overflow_size_tls
+
+; Check multiple fixed arguments.
+declare i32 @foo2(i32 %g1, i32 %g2, ...)
+define i32 @bar2() {
+  %1 = call i32 (i32, i32, ...) @foo2(i32 0, i32 1, i64 2, double 3.000000e+00)
+  ret i32 %1
+}
+
+; CHECK-LABEL: @bar2
+; CHECK: store i64 0, i64* getelementptr inbounds ([100 x i64], [100 x i64]* @__msan_va_arg_tls, i32 0, i32 0), align 8
+; CHECK: store i64 0, i64* inttoptr (i64 add (i64 ptrtoint ([100 x i64]* @__msan_va_arg_tls to i64), i64 8) to i64*), align 8
+; CHECK: store {{.*}} 16, {{.*}} @__msan_va_arg_overflow_size_tls

test/Instrumentation/MemorySanitizer/Mips/vararg-mips64el.ll

 
 ; Save the incoming shadow value from the arguments in the __msan_va_arg_tls
 ; array.
 ; CHECK-LABEL: @bar
 ; CHECK: store i32 0, i32* bitcast ([100 x i64]* @__msan_va_arg_tls to i32*), align 8
 ; CHECK: store i64 0, i64* inttoptr (i64 add (i64 ptrtoint ([100 x i64]* @__msan_va_arg_tls to i64), i64 8) to i64*), align 8
 ; CHECK: store i64 0, i64* inttoptr (i64 add (i64 ptrtoint ([100 x i64]* @__msan_va_arg_tls to i64), i64 16) to i64*), align 8
 ; CHECK: store {{.*}} 24, {{.*}} @__msan_va_arg_overflow_size_tls
+
+; Check multiple fixed arguments.
+declare i32 @foo2(i32 %g1, i32 %g2, ...)
+define i32 @bar2() {
+  %1 = call i32 (i32, i32, ...) @foo2(i32 0, i32 1, i64 2, double 3.000000e+00)
+  ret i32 %1
+}
+
+; CHECK-LABEL: @bar2
+; CHECK: store i64 0, i64* getelementptr inbounds ([100 x i64], [100 x i64]* @__msan_va_arg_tls, i32 0, i32 0), align 8
+; CHECK: store i64 0, i64* inttoptr (i64 add (i64 ptrtoint ([100 x i64]* @__msan_va_arg_tls to i64), i64 8) to i64*), align 8
+; CHECK: store {{.*}} 16, {{.*}} @__msan_va_arg_overflow_size_tls